Method and apparatus for improving safety during exposure to a monochromatic light source

ABSTRACT

A method and apparatus are disclosed for enhancing the absorption of light in targeted skin structures. A vacuum chamber having a clear transmitting element transparent to intense pulsed light on its proximate end and an aperture on its distal end is placed on a skin target. After applying a vacuum to the vacuum chamber and modulating the applied vacuum, the concentration of blood and/or blood vessels is increased within a predetermined depth below the skin surface of the skin target. Optical energy associated with intense pulsed light directed in a direction substantially normal to a skin surface adjoining the skin target is absorbed within the predetermined depth. The apparatus is suitable for treating vascular lesions with a reduced treatment energy density level than that of the prior art and for evacuating condensed vapors produced during the cooling of skin prior to firing an intense pulsed light with a controlled delay.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of international applicationno. PCT/IL02/00635, filed on Aug. 2, 2002, which claims the benefit ofand priority to Israeli patent application no. 147009, filed on Dec. 10,2001, and Israeli patent application no. 150094, filed on Jun. 6, 2002.This application also claims the benefit of and priority to Israelipatent application no. 160510, filed on Feb. 22, 2004. This applicationis also a continuation-in-part of U.S. application Ser. No. 10/614,672,filed Jul. 7, 2003, now U.S. Pat. No. 7,184,614.

FIELD OF THE INVENTION

The present invention is related to the field of laser-based lightsources. More specifically, the invention is related to the utilizationof light sources for the non-invasive treatment of skin disorders,whereby light is selectively absorbed by blood vessels, for thetreatment or destruction of blood vessels.

BACKGROUND OF THE INVENTION

Prior art very high intensity, short duration pulsed light systems whichoperate in the visible part of the spectrum, such as flashlamps orintense pulsed lasers are currently used in aesthetic treatments by oneof two known ways: a) Applying the light to the skin without applyingany pressure on the treatment zone, so as not to interfere with thenatural absorption properties of skin; and b) Applying pressure onto theskin by means of the exit window of the treatment device in contact withthe skin, thereby expelling blood from the light path within the skinand enabling better transmission of the light to a skin target.

The major applications of intense pulsed light or intense pulsed lasersystems are hair removal, coagulation of blood vessels for e.g. portwine stains, telangectasia, spider veins and leg veins, multiple heatingof blood vessels for e.g. rosacea, treatment of pigmented skin such aserasure of black stains and sun stains or tattoo removal; and removal offine wrinkles by heating the tissue around the wrinkles, normallyreferred to as photorejuvenation.

U.S. Pat. Nos. 5,226,907, 5,059,192, 5,879,346, 5,066,293, 4,976,709,6,120,497, 6,120,497, 5,626,631, 5,344,418, 5,885,773, 5,964,749,6,214,034 and 6,273,884 describe various laser and non-coherent intensepulsed light systems. These prior art light systems are not intended toincrease the natural absorption of the skin.

U.S. Pat. Nos. 5,595,568 and 5,735,844 describe a system for hairremoval whereby pressure is applied to the skin by a transparent contactdevice in contact therewith, in order to expel blood present in bloodvessels from a treatment zone. In this approach blood absorptiondecreases in order to increase subcutaneous light penetration.

Applying a vacuum to the skin is a known prior art procedure, e.g. forthe treatment of cellulites, which complements massaging the skin. Sucha procedure produces a flow of lymphatic fluids so that toxic substancesmay be released from the tissue. As the vacuum is applied, a skin foldis formed. The skin fold is raised above the surrounding skin surface,and the movement of a handheld suction device across the raised skinperforms the massage. The suction device is moved in a specificdirection relative to the lymphatic vessels, to allow lymphatic fluidsto flow in their natural flow direction. The lymphatic valve in eachlymphatic vessel prevents the flow of lymphatic fluid in the oppositedirection, if the suction device were moved incorrectly. Liquidsgenerally accumulate if movement is not imparted to the raised skin. Themassage, which is generally carried out by means of motorized or handdriven wheels or balls, draws lymphatic fluids from cellulite in theadipose subcutaneous region and other deep skin areas, the depth beingapproximately 5-10 mm below the dermis.

U.S. Pat. No. 5,961,475 discloses a massaging device with which negativepressure is applied to the skin together during massaging. A similarmassaging device which incorporates a radio frequency (RF) source forthe improvement of lymphatic flow by slightly heating the adipose tissueis described in U.S. Pat. No. 6,662,054. Some massaging systems, such asthose produced by Deka and Cynosure, add a low power, continuous working(CW) light source of approximately 0.1-2 W/cm², in order to provide deepheating of the adipose tissue by approximately 1.3° C. degrees and toenhance lymphatic circulation. The light sources associated with vacuumlymphatic massage devices are incapable of inducing blood vesselcoagulation due to their low power. Also, prior art vacuum lymphaticmassage devices are adapted to induce skin protrusion or to produce askin fold by applying a vacuum.

Selective treatment of blood vessels by absorption of intense pulsedlaser radiation is possible with Dye lasers operating at 585 nm, as wellas with other types of lasers. Photorejuvenation has also been performedwith Diode lasers in the near infrared spectral band of 800-980 nm andwith Nd:YAG lasers having a frequency of approximately 1064 nm withlimited success. The light emitted by such lasers is not well absorbedby tiny blood vessels or by the adjoining liquid. Broad bandnon-coherent intense pulsed light systems are also utilized forphotorejuvenation with some success, although requiring more than 10repeated treatments. The heat which is absorbed by the blood vessels, asa result of the light emitted by the intense short pulse devices, istransferred to adjacent collagen bundles.

The absorption of pulsed Diode and Nd:YAG laser beams by blood vesselsis lower than the absorption of pulsed Dye laser beam. In order tocompensate for limited photorejuvenation with red and infrared intensepulsed light and laser systems, a very high energy density as high as30-60 J/cm² needs to be generated. At such an energy density, themelanin-rich epidermis, particularly in dark skin, is damaged if notchilled. A method to reduce the energy density of intense pulsed lasersor non-coherent intense pulsed light sources which operate in thevisible or the near infrared regions of the spectrum will thereforebeneficial.

Pulsed dye lasers operating in the yellow spectral band of approximately585-600 nm, which is much better absorbed by blood vessels, are alsoutilized for the smoothing of fine wrinkles. The energy density of lightemitted by Dye lasers, which is approximately 3-5 J/cm², is much lowerthan that of light emitted by other lasers. However, the pulse durationsof light emitted by Dye lasers are very short, close to 1 microsecond,and therefore risk the epidermis in darker skin. Treatments of wrinkleswith Dye lasers are slow, due to the low concentration of absorbingblood vessels, as manifested by the yellow or white color of treatedskin, rather than red or pink characteristic of skin having a highconcentration of blood vessels. Due to the low energy density of lightemitted by Dye lasers, as many as 10 treatments may be necessary. Amethod to reduce the energy density of light generated by Dye lasers, orto reduce the number of required treatments at currently used energydensity levels, for the treatment of fine wrinkles, would be beneficial.

Pulsed Dye lasers operating at 585 nm are also utilized for thetreatment of vascular lesions such as port wine stains or telangectasiaor for the treatment of spider veins. The energy density of the emittedlight is approximately 10-15 J/cm², and is liable to cause a burn whilecreating the necessary purpura. A method to reduce the energy density oflight emitted by Dye lasers for the treatment of vascular lesions wouldbe highly beneficial.

Hair removal has been achieved by inducing the absorption of infraredlight, which is not well absorbed by melanin present in hair strands,impinging on blood vessels. More specifically, absorption of infraredlight by blood vessels at the distal end of hair follicles contributesto the process of hair removal. High intensity pulsed Nd:YAG lasers,such as those produced by Altus, Deka, and Iridex, which emit lighthaving an energy density of more than 50 J/cm², are used for hairremoval. The light penetration is deep, and is often greater than 6millimeters. Some intense pulsed light or pulsed laser systems, such asthat produced by Syneron, used for hair removal or photorejuvenationalso employ an RF source for further absorption of energy within theskin.

The evacuation of smoke or vapor, which is produced following theimpingement of monochromatic light on a skin target, from the gapbetween the distal end window of a laser system and the skin target, iscarried out in conjunction with prior art ablative laser systems such asCO₂, Erbium or Excimer laser systems. The produced smoke or vapor ispurged by the introduction of air at greater than atmospheric pressure.Coagulative lasers such as pulsed dye lasers or pulsed Nd:YAG lasers,which treat lesions under the skin surface, are not provided with anevacuation chamber.

Some prior art intense pulsed laser systems, which operate in thevisible and near infrared region of the spectrum and treat lesions underthe skin surface, e.g. vascular lesions, with pulsed dye laser systemsor pulsed Nd:YAG lasers, employ a skin chilling system. Humiditygenerally condenses on the distal window, due to the use of a skinchilling system. It would be advantageous to evacuate the condensedvapors from the distal window of the laser system prior to the nextfiring of the laser.

It is an object of the present invention to provide a method andapparatus for the treatment of subcutaneous lesions, such as vascularlesions, by a high intensity pulsed laser system operating atwavelengths shorter than 1800 nm without causing a burn to theepidermis.

It is an object of the present invention to provide a method andapparatus for controlling the depth of subcutaneous light absorption.

It is an object of the present invention to provide a method andapparatus for increasing the absorption of light which impinges a skintarget by increasing the concentration of blood vessels thereat.

It is an additional object of the present invention to provide a methodand apparatus by which the energy density level of intense pulsed lightthat is suitable for hair removal, fine wrinkle removal, includingremoval of wrinkles around the eyes and in the vicinity of the hands orthe neck, and the treatment of port wine stain or rosacea may be reducedrelative to that of the prior art.

It is an additional object of the present invention to provide a methodand apparatus by which the number of required treatments for hairremoval, fine wrinkle removal, including removal of wrinkles around theeyes and in the vicinity of the hands or the neck, and the treatment ofport wine stain or rosacea at currently used energy density levels maybe reduced relative to that of the prior art.

It is yet an additional object of the present invention to provide amethod and apparatus for repeated evacuation, prior to the firing of asubsequent laser pulse, of vapors which condensed on the distal windowdue to the chilling of laser treated skin.

Other objects and advantages of the invention will become apparent asthe description proceeds.

SUMMARY OF THE INVENTION

The present invention comprises a method for controlling the depth oflight absorption by blood vessels under a skin surface comprisingplacing a vacuum chamber which is transparent to intense pulsed light ona skin target; applying a vacuum to said vacuum chamber, whereby saidskin target is drawn to said vacuum chamber and the concentration ofblood and/or blood vessels within said skin target is increased;modulating the applied vacuum so that the concentration of blood and/orblood vessels is increased within a predetermined depth below the skinsurface; and directing intense pulsed light to said skin target, opticalenergy associated with the directed intense pulsed light being absorbedwithin said predetermined depth.

The depth under the skin surface at which optical energy is absorbed maybe selected in order to thermally injure or treat predetermined skinstructures located at said depth. As referred to herein, a “skinstructure” is defined as any damaged or healthy functional volume ofmaterial located under the epidermis, such as blood vessels, collagenbundles, hair shafts, hair follicles, sebaceous glands, sweat glands,adipose tissue. Depending on the blood concentration within the skintarget, the intense pulsed light may propage through the skin surfaceand upper skin layers without being absorbed thereat and then beingabsorbed at a skin layer corresponding to that of a predetermined skinstructure. As referred to herein, the term “light” means bothmonochromatic and non-coherent light. The terms “light absorption” and“optical energy absorption” refer to the same physical process and aretherefore interchangeable.

In contrast with a prior art vacuum-assisted method of laser or intensepulsed light treatment wherein a skin fold is produced followingapplication of the vacuum, vacuum-assisted drawn skin in accordance withthe method of the present invention is not distorted, but rather isslightly and substantially uniformly drawn to the vacuum chamber,protruding approximately 1 mm from the adjoining skin surface. Themaximum protrusion of the drawn skin from the adjoining skin surface islimited by a clear transmitting element defining the proximate end ofthe vacuum chamber. The clear transmitting element is separated from theadjoining skin surface by a gap of preferably 2 mm, and ranging from0.5-40 mm.

As referred to herein, “vacuum modulation” means adjustment of thevacuum level within, or of the frequency by which vacuum is applied to,the vacuum chamber. By properly modulating the vacuum, the blood flowrate, in a direction towards the vacuum chamber, within blood vessels ata predetermined depth below the skin surface can be controlled. As theconcentration of blood and/or blood vessels is increased within the skintarget, the number of light absorbing chromophores is correspondinglyincreased at the predetermined depth. The value of optical energyabsorbence at the predetermined depth, which directly influences theefficacy of the treatment for skin disorders, is therefore increased.

Preferably

-   -   a) The wavelength of the intense pulsed light ranges from 400 to        1800 nm.    -   b) The pulse duration of the intense pulsed light ranges from 10        nanoseconds to 900 msec.    -   c) The energy density of the intense pulsed light ranges from 2        to 150 J/cm².    -   d) The level of the applied vacuum within the vacuum chamber        ranges from 0 to 1 atmosphere.    -   e) The frequency of vacuum modulation ranges from 0.2 to 100 Hz.    -   f) The intense pulsed light is fired after a predetermined delay        following application of the vacuum.    -   g) The predetermined delay ranges from 10 msec to 1 second.    -   h) The duration of vacuum application to the vacuum chamber is        less than 2 seconds.    -   i) Vacuum modulation is electronically controlled.

Due to implementation of the method of the present invention, thetreatment energy density level for various types of treatment issignificantly reduced, on the average of 50% with respect with thatassociated with prior art devices. The treatment energy density level isdefined herein as the minimum energy density level which creates adesired change in the skin structure, such as coagulation of a bloodvessel, denaturation of a collagen bundle, destruction of cells in agland, destruction of cells in a hair follicle, or any other desiredeffects. The following is the treatment energy density level for varioustypes of treatment performed with use of the present invention:

-   -   a) treatment of vascular lesions, port wine stains,        telangectasia, rosacea, and spider veins with light emitted from        a dye laser unit and having a wavelength of 585 nm: 5.12 J/cm²;    -   b) treatment of vascular lesions, port wine stains,        telangectasia, rosacea, and spider veins with light emitted from        a diode laser unit and having a wavelength of 940 nm: 10-30        J/cm²;    -   c) treatment of vascular lesions with light emitted from an        intense pulsed non-coherent light unit and having a wavelength        of 570-900 nm: 5-20 J/cm²;    -   d) photorejuvination with light emitted from a dye laser unit        and having a wavelength of 585 nm: 1-4 J/cm²;    -   e) photorejuvination with light emitted from an intense pulsed        non-coherent light unit and having a wavelength of 570.900 nm:        5.20 J/cm²;    -   f) photorejuvination with a combined effect of light emitted        from an intense pulsed non-coherent light unit and having a        wavelength of 570-900 nm and of a RF source: 10 J/cm² for both        the intense pulsed non-coherent light unit and RF source; and    -   g) hair removal with light emitted from a Nd:YAG laser unit and        having a wavelength of 1604 nm: 25.35 J/cm².

The present invention is also directed to an apparatus for enhancing theabsorption of light in targeted skin structures, comprising:

-   -   a) a vacuum chamber placed on a skin target which is formed with        an aperture on the distal end thereof and provided with a clear        transmitting element on the proximate end thereof, said        transmitted element being transparent to intense pulsed light        directed to said skin target and suitable for transmitting the        intense pulsed light in a direction substantially normal to a        skin surface adjoining said skin target;    -   b) means for applying a vacuum to said vacuum chamber, the level        of the applied vacuum suitable for drawing said skin target to        said vacuum chamber via said aperture; and    -   c) means for modulating the applied vacuum in such a way that        the concentration of blood and/or blood vessels is increased        within a predetermined depth below the skin surface of said skin        target, optical energy associated with the directed intense        pulsed light being absorbed within said predetermined depth.

As referred to herein, “distal” is defined as a direction towards theexit of the light source and “proximate” is defined as a directionopposite from a distal direction.

The ratio of the maximum length to maximum width of the aperture formedon the distal end of the vacuum chamber ranges from approximately 1 to4.

In one embodiment of the invention, the vacuum chamber is connected to,or integrally formed with, a proximately disposed handpiece throughwhich intense pulsed light propagates towards the skin target.

The intense pulsed light is suitable for hair removal,photorejuvenation, treatment of vascular lesions, treatment of sebaceousor sweat glands, treatment of warts, or treatment of pigmented lesions.

The present invention is also directed to an apparatus for enhancing theabsorption of light in targeted skin structures, comprising:

-   -   a) an intense pulsed light source;    -   b) a U-shaped evacuation chamber positionable on a skin target;    -   c) a handpiece for directing intense pulsed light to a skin        target which is connected to, or integral with, said evacuation        chamber;    -   d) a clear transmitting element mounted in the distal end of        said handpiece, said transmitted element being transparent to        intense pulsed light directed to said skin target and suitable        for transmitting the intense pulsed light in a direction        substantially normal to a skin surface adjoining said skin        target;    -   e) a rim for sealing the peripheral contact area between the        skin surface adjoining said skin target and the wall of the        handpiece; and    -   f) means for applying a vacuum to said evacuation chamber, the        level of the applied vacuum suitable for drawing said skin        target to said evacuation chamber and for increasing the        concentration of blood and/or blood vessels within a        predetermined depth below the skin surface of said skin target,        optical energy associated with the directed intense pulsed light        being absorbed within said predetermined depth.

The terms “evacuation chamber” and “vacuum chamber” as referred toherein are interchangeable.

The vacuum applying means preferably comprises a vacuum pump and atleast one control valve.

The apparatus preferably further comprises control means for controllingoperation of the vacuum pump, the at least one control valve, and theintense pulsed light source. The control means is suitable for firingthe intense pulsed light source after a predetermined delay followingoperation of the vacuum pump. Alternatively, the control means issuitable for firing the intense pulsed light source after apredetermined delay following opening of the at least one control valve.

The control means is also suitable for increasing the pressure in theevacuation chamber to atmospheric pressure following deactivation of theintense pulsed light source, to allow for effortless repositioning ofthe evacuation chamber to a second skin target.

The intense pulsed light source is selected from the group of Dye laser,Nd:YAG laser, Diode laser, Alexandrite laser, Ruby laser, Nd:YAGfrequency doubled laser, Nd:Glass laser and a non-coherent intense pulselight source. The light emitted from the light source has any wavelengthband between 400 nm and 1800 nm.

In one aspect, the apparatus further comprises a pulsed radio frequency(RF) source for directing suitable electromagnetic waves to the skintarget. The frequency of the electromagnetic waves ranges from 0.2-10MHz. The RF source is preferably a bipolar RF generator which generatesalternating voltage applied to the skin surface via wires andelectrodes. The control means is suitable for transmitting a firstcommand pulse to the at least one control valve and a second commandpulse to both the intense pulsed light source and RF source.

In one aspect, the apparatus further comprises an erythema sensor, saidsensor suitable for measuring the degree of skin redness induced by thevacuum applying means. The control means is suitable for controlling,prior to firing the light source, the energy density of the lightemitted from the light source, in response to the output of the erythemasensor.

The present invention is also directed to an apparatus for treatingvascular lesions, comprising:

-   -   a) a Dye laser unit;    -   b) a vacuum chamber placed on a skin target which is formed with        an aperture on the distal end thereof and provided with a clear        transmitting element on the proximate end thereof, said        transmitted element being transparent to light which is emitted        from the laser unit and directed to said skin target and being        suitable for transmitting the light in a direction substantially        normal to a skin surface adjoining said skin target;    -   c) a handpiece which is connected to, or integral with, said        vacuum chamber, for directing light to a skin target;    -   d) a rim for sealing the peripheral contact area between the        skin surface adjoining said skin target and the wall of the        handpiece;    -   e) a vacuum pump for applying a vacuum to said vacuum chamber,        the level of the applied vacuum suitable for drawing said skin        target to said vacuum chamber via said aperture;    -   f) a control unit for controlling operation of the vacuum pump        and laser unit; and    -   g) means for modulating the applied vacuum by said control unit        in such a way that the concentration of blood and/or blood        vessels is increased within a predetermined depth below the skin        surface of said skin target, optical energy associated with the        directed intense pulsed light capable of being absorbed within        said predetermined depth and treating a vascular lesion.

The present invention also comprises an apparatus for evacuatingcondensed vapors produced during the cooling of skin prior to firing anintense pulsed light, comprising:

-   -   a) a vacuum chamber having a proximate end and positionable on a        skin target such that a gap is formed between the proximate end        thereof and the skin target, said proximate end being        transparent to intense pulsed light directed to said skin target        and to targeted skin structures located below the epidermis        within the projected area of the proximate end and suitable for        transmitting the intense pulsed light in a direction        substantially normal to a skin surface adjoining said skin        target;    -   b) means for skin cooling, said skin cooling means adapted to        reduce the rate of temperature increase of the epidermis at the        skin target; and    -   c) means for applying a vacuum to said vacuum chamber, the level        of the applied vacuum suitable for—        -   i. drawing said skin target to said vacuum chamber;        -   ii. increasing the concentration of blood and/or blood            vessels within a predetermined depth below the skin surface            of said skin target corresponding with the depth of said            targeted skin structures, optical energy associated with the            directed intense pulsed light being absorbed within said            targeted skin structures; and        -   iii. evacuating condensed vapors which are produced within            said gap and condense on said proximate end during the            cooling of skin.

In one aspect, the skin cooling means is a metallic plate in abutmentwith said vacuum chamber on the external side thereof and positionableon the skin surface adjoining said skin target, said plate being cooledby means of a thermoelectric cooler operative to cool the lateral sidesof the vacuum chamber.

In another aspect, the skin cooling means is a gel, a low temperatureliquid or gas applied onto the skin target.

The present invention is also directed to a method for treatment oflesions by the absorption of light in targeted skin structures,comprising the steps of:

-   -   a) placing a U-shaped vacuum chamber which is transparent to        intense pulsed light and provided with two opposed conduits on a        skin target;    -   b) applying a vacuum to said vacuum chamber via a first conduit;    -   c) increasing the vacuum level within said vacuum chamber by        occluding a second conduit, whereby said skin target is drawn to        said vacuum chamber and the concentration of blood and/or blood        vessels at a predetermined depth below the skin surface of said        skin target is increased;    -   d) firing the intense pulsed light source after a predetermined        delay following step c) such that intense pulsed light is        directed to targeted skin structures below said skin target,        optical energy associated with the directed intense pulsed light        capable of being absorbed within said predetermined depth and        treating a lesion.

In one aspect, the second conduit is occluded by placement of a fingerthereon.

In one aspect, the method further comprises the steps of increasing thepressure within the vacuum chamber to atmospheric pressure by openingthe second conduit and repositioning the vacuum chamber.

The lesions are selected from the group of vascular lesions includingport wine stains, telangectasia, rosacea, spider veins, unwanted hairs,damaged collagen, acne, warts, keloids, sweat glands, and psoriasis.

The present invention also comprises a method for evacuating condensedvapors produced during the cooling of skin prior to firing an intensepulsed light, comprising:

-   -   a) placing a U-shaped vacuum chamber which is transparent to        intense pulsed light and provided with two opposed conduits on a        skin target;    -   b) chilling the skin target;    -   c) applying a vacuum to said vacuum chamber via a first conduit;    -   d) increasing the vacuum level within said vacuum chamber by        occluding a second conduit, whereby said skin target is drawn to        said vacuum chamber and the concentration of blood and/or blood        vessels at a predetermined depth below the epidermis of said        skin target is increased;    -   e) firing the intense pulsed light source after a predetermined        delay following step d) such that intense pulsed light is        directed to targeted skin structures below said skin target,        optical energy associated with the directed intense pulsed light        capable of being absorbed within said predetermined depth and        treating a lesion.    -   f) evacuating condensed vapors which are produced within said        gap during the cooling of skin prior to firing an intense pulsed        light.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 illustrates a side view of various laser units equipped with adiffusing unit, in accordance with the present invention, wherein thedelivery system shown in FIG. 1 a is an articulated arm, in FIG. 1 b isan optical fiber and in FIG. 1 c is a conical light guide;

FIG. 2 illustrates a side view of the distal end of a laser unit,showing how the diffusing unit is attached thereto, wherein thediffusing unit is externally attached to the guide tube in FIG. 2 a, isattached to a pointer in FIG. 2 b, is releasably attached to the guidetube in FIG. 2 c, is integrally formed together with the guide tube inFIG. 2 d and is displaceable in FIG. 2 e whereby at one position theexit beam propagates therethrough and at a second position the exit beamdoes not propagate therethrough;

FIG. 3 is a schematic diagram of various configurations of prior artlaser units, wherein FIG. 3 a shows a non-scattered beam directed byreflectors to a target, FIG. 3 b shows a non-scattered beam directed byan optical fiber to a target, FIG. 3 c illustrates prior art surgeryperformed with a laser beam and scanner, FIG. 3 d shows the propagationof prior art refracted laser beams towards a blood vessel, FIG. 3 eshows an ablative laser beam focused on tissue in conjunction with ascanner, and FIG. 3 f shows the formation of a crater in tissue by anablative beam;

FIG. 4 is a schematic diagram illustrating the advantages of employing adiffusing unit of the present invention, wherein FIG. 4 a shows therelative location of the diffusing unit, FIG. 4 b shows that acollimated laser beam is transformed into a randomly scattered beam,FIG. 4 c shows that a scattered beam reduces risk of injury to the skinand FIG. 4 d shows that a collimated laser beam reduces risk of injuryto the eyes;

FIG. 5 is a schematic drawing showing the propagation of a laser beamtowards a blood vessel, wherein FIG. 5 a shows the propagation of anunscattered laser beam towards a blood vessel, FIG. 5 b shows thepropagation of a scattered laser beam towards a blood vessel, FIG. 5 cillustrates the formation of an ablation by means of an unscatteredlaser beam. FIG. 5 d illustrates the formation of an ablation by meansof an scattered laser beam in accordance with the present invention, andFIG. 5 e illustrates the scattering of a laser beam distant from a bloodvessel;

FIG. 6 a is a schematic drawing showing the accumulation of liquidresidue on a diffusively transmitting element and FIG. 6 b is aschematic drawing in which a diffusively transmitting element is shownto be mounted within a hermetically sealed diffusing unit;

FIG. 7 illustrates the production of a plurality of microlenses, whereinFIG. 7 a illustrates the sandblasting of a metallic plate, FIG. 7 billustrates the addition of a liquid sensitive to ultraviolet light,FIG. 7 c illustrates the removal of the metallic plate and FIG. 7 dillustrates the generation of a scattered laser beam through themicrolenses;

FIG. 8 illustrates two types of a diffusing unit, wherein FIG. 8 aillustrates one employing a single wide angle diffuser and FIG. 8 billustrates one employing a small angle diffuser;

FIG. 9 illustrates a diffusing unit which employs a tapered light guide,such that the light guide receives monochromatic light from an opticalfiber in FIG. 9 a and from an array of microlenses in FIG. 9 b;

FIG. 10 illustrates a diffusing unit which utilizes an angular beamexpander without a light guide in FIG. 10 a and with a light guide inFIG. 10 b;

FIG. 11 illustrates a diffusing unit which employs two holographicdiffusers, each of which is attached to a corresponding light guide;

FIG. 12 illustrates a diffusing unit which includes two diffusers, oneof which is axially displaceable, wherein FIG. 12 a illustrates the unitin an active position and FIG. 12 b in an inactive position;

FIG. 13 is a schematic drawing of another preferred embodiment of thepresent invention in which a scanner rapidly repositions a coherentlaser beam onto a plurality of targets on a diffusively transmittingelement;

FIG. 14 is another preferred embodiment of the present invention inwhich a non-scattering diverging unit is used to diverge an input laserbeam, wherein FIG. 14 a illustrates a single optical element and FIG. 14b illustrates a plurality of elements;

FIG. 15 is a schematic diagram of various means of cooling skin duringlaser-assisted cosmetic surgery, wherein FIGS. 15 a-d are prior artmeans, while FIG. 15 e utilizes cooling fluid and FIG. 15 f utilizes athermoelectric cooler;

FIG. 16 illustrates an eye safety measurement device;

FIG. 17 schematic drawing of a flashing device, wherein FIG. 17 aillustrates one that induces uncontrolled blinking before firing a laserbeam, FIG. 17 b is a timing diagram corresponding to the flashing deviceof FIGS. 17 a, and 17 c illustrates a flashing device that detects aretroreflected beam from an eye within firing range of a laser beam;

FIG. 18 is a schematic drawing which illustrates the propagation of anintense pulsed laser beam from a handpiece to a skin target according toa prior art method;

FIG. 19 is a schematic drawing which illustrates the propagation of anintense pulsed non-coherent light beam from a handpiece to a skin targetaccording to a prior art method;

FIG. 20 is a schematic drawing of a prior art treatment method by whichpressure is applied to a skin target, in order to expel blood from thoseportions of blood vessels which are in the optical path ofsubcutaneously scattered light;

FIG. 21 is a schematic drawing of a prior art vacuum-assisted rollingcellulite massage device;

FIG. 22 is a schematic drawing of a prior art vacuum-assisted hairremoval device adapted to reduce the blood concentration within a skinfold formed thereby, in order to illuminate two opposed sides of theskin fold and consequently remove melanin-rich hair shafts;

FIG. 23 is a schematic drawing of apparatus in accordance with oneembodiment of the present invention, employing a manually occludedU-shaped evacuation chamber;

FIG. 24 is a schematic drawing of apparatus in accordance with anotherembodiment of the present invention, employing an electronicallyoccluded evacuation chamber;

FIG. 25 is a schematic drawing of apparatus in accordance with thepresent invention, employing an intense pulsed non coherent lightsource;

FIG. 26 is a schematic drawing of apparatus in accordance with thepresent invention, which is provided with a skin chiller;

FIG. 27 is a drawing which schematically illustrates the effect ofapplying a subatmospheric pressure to a vacuum chamber in order toincrease the blood concentration in skin drawn towards the vacuumchamber;

FIG. 28 is a drawing which schematically illustrates the increasedconcentration of a plurality of blood vessels in a skin target followingapplication of a vacuum to a vacuum chamber, resulting in increasedredness of skin and enhanced absorption of light;

FIG. 29 is a photograph illustrating the change in skin color followingtreatment of a fine wrinkle by use of a vacuum assisted handpiece inaccordance with the present invention;

FIG. 30 is a schematic drawing of another embodiment of the invention,illustrating propagation of intense pulsed light from an external lightsource to a transparent modulated vacuum chamber; and

FIG. 31 schematically illustrates another embodiment of the inventionwhich employs both an intense pulsed light source and a radio frequencysource, for improved coagulation of blood vessels.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 a illustrates a high-intensity laser unit, generally designatedby 10, which is suitable for use with the present invention. Laser unit10 operates at a wavelength ranging between 300 and 1600 nm or between1750 nm and 11.5 microns, either pulsed, with a pulse duration of 1nanosecond to 1500 milliseconds and an energy density of 0.01.200 J/cm²,or continuous working with a power density higher than 1 W/cm². Laserunit 10 is provided with a diffusing unit, generally designated by 15,which induces the exit beam to be scattered. An exit beam is consideredto be scattered according to this embodiment when its average half angleangular divergence is greater than 42 degrees relative to thepropagation axis of collimated beam 4. A half angle of 60 degreescorresponds to the half angle generated by an “ideal transmittingdiffuser,” which herein refers to a diffuser with 100% transmission andis provided with Lambertian angular scattering properties. Such ascattering angle, in accordance with the present invention, allows thelight which exits diffusing unit 15 to be safe to the eyes of abystander, yet is provided with a sufficiently high energy density whichis necessary for the clinical efficacy of the laser unit.

Laser unit 10 comprises amplifying medium 1 activated by power supply 2for increasing the intensity of a light beam and two parallel mirrors 3that provide feedback of the amplified beam into the amplifying medium,thereby generating a coherent beam of ultrapure frequency. The laserunit emits a coherent beam 4 which propagates through a delivery system5 to distal end 6. The delivery system depicted in FIG. 1 a isarticulated arm 7 a. Diffusing unit 15 is fixedly attached to the distalend of guidance tube 12 by attachment means 16, which may be a set ofscrews or by bonding or other means known to those skilled in the art,thereby inducing non coherent randomly scattered beam 14 associated witha narrow spectral bandwidth that does not present any risk of damage tobodily tissue if the laser is inadvertently directed to an incorrecttarget. The diffusing unit includes a passive refractive element thatpreserves the wavelength of coherent beam 4, as well as its narrowbandwidth, which is generally less than one Angstrom.

In one preferred embodiment of the invention, diffusing unit 15 ispreferably cylindrical or rectangular, although any other geometricalshape is equally suitable, and comprises diffusively transmittingelement 13, which is proximate to distal end 6 of the laser unit andclear transmitting element 17. Both diffusively transmitting element 13and clear transmitting element 17 have the same dimensions and arebonded to diffusing unit 15. Diffusively transmitting element 13 andclear transmitting element 17 are preferably separated by narrow gap 18.Due to the existence of gap 18, the laser beam will remain scatteredeven if clear transmitting element 17 shatters, thereby preserving theinherent safety of a laser unit that incorporates the present invention.The width of gap 18 is as small as possible, usually 0.1 mm. However,diffusing unit 15 may be adapted to a configuration in which diffusivelytransmitting element 13 contacts clear transmitting element 17.Alternatively, diffusing unit may be provided without a cleartransmitting element, whereby the frosted surface of diffusivelytransmitting element 13 faces the laser unit and its smooth surfacefaces the tissue.

Scattering is achieved by means of minute irregularities of anon-uniform diameter formed on the substrate of diffusively transmittingelement 13. Diffusively transmitting element 13 is preferably producedfrom thin sand blasted or chemically etched glass, e.g. having athickness from 0.1 to 0.2 mm, or a thin sheet of non-absorbing lightdiffusing polymer, e.g. having a thickness of less than 50 microns, suchas light diffusing polycarbonate, Mylar or acrylic.

A diffusively transmitting element may also be produced by using a largeangle holographic diffuser such as one produced by Physical OpticsCorporation (PCO), USA, and is placed adjacent to an additionaldiffuser. A holographic diffuser illustrated in FIG. 11 induces ascattering half angle, for example, of at least 40 degrees and thesecond diffuser additionally induces the scattering so as to attain ascattering half angle of e.g. 60 degrees.

A diffuser which approaches an ideal transmitting diffuser and induces ascattering half angle of 60 degrees and a scattering solid angle of 3.14sr may be produced from material such as acrylic or polycarbonate bypressing the material against an appropriate surface provided with avery dense array of Frensnel microlenses, such as those produced byFresnel Technologies Inc., USA, or by placing arrays of microlensessurfaces separated from a light guide as depicted in FIG. 9 b.

Similarly diffusively transmitting element 13 may be produced from lightdiffusing paper such as transparent “Pergament” drawing paper, and mayalso be produced from other materials such as ZnSe, BaF₂, and NaCl,depending on the application and the type of laser used. Both faces ofclear transmitting element 17 are essentially planar and smooth. Cleartransmitting element 17, which is capable of withstanding the thermalstress imposed by a scattered laser beam, is transparent and made fromsapphire, glass, a polymer such as polycarbonate or acrylic, and may beproduced from other materials as well, such as ZnF₂.

Diffusively transmitting element 13 may be chilled so that it will becapable of withstanding the high power densities which are necessary forattaining clinical efficacy.

As depicted in FIG. 1 b, the delivery system may also be optical fiber 7b into which laser beam 4 is focused. Diffusing unit 15 is mounted onguidance tube 8, which directs the beam exiting the distal end ofoptical fiber 7 b by attachment means 16. Furthermore, as depicted inFIG. 1 c, the laser unit may be comprised of array 11 of miniaturelasers, such as those provided with high power diode lasers, e.g. theLightsheer produced by Coherent, USA, for hair removal. The beamdelivery system for this configuration is preferably conical reflector 7c. In this configuration, diffusing unit 15 is fixed to distal end 6 oflight guide 7 c and transforms a high-risk beam into randomly scatteredbeam 14.

FIG. 2 illustrates various methods by which diffusing unit 15 isattached to a laser unit. In FIG. 2 a, bracket 19 which supportsdiffusing unit 15 is attached to guidance tube 12 of an existing laserunit, such as one in use in a clinic, by attachment means 16 a, whichmay be a set of screws or by bonding. As shown in FIG. 2 b the laserunit is provided with pointer 31, or any other equivalent subdiffusingunit which enables the user to direct beam 4 to a desired target on theskin, by the focal length and beam diameter which are dictated by lens 9mounted within guidance tube 12. In this alternative, diffusing unit 15may be externally attached to guidance tube 12, or may be attached topointer 19. In FIG. 2 c, diffusing unit 15 is attached to Velcro tape 16c, or another type of adhesive tape. This type of attachment means issufficient for temporary usage. In FIG. 2 d, diffusing unit 15 isintegrally formed together with guidance tube 12 during manufacturing,internal to the outer wall thereof. FIG. 2 e illustrates a releasableattachment means, whereby in one position of a displaceable diffusingunit the exit beam is coherent, not propagating through a diffusivelytransmitting element, and in a second position in which diffusing unit15 is attached to guidance tube 12, the exit beam is noncoherent andpropagates through a diffusively transmitting element.

In prior art cosmetic laser surgery, as shown in FIG. 3 a, laser unit 20emits a non-scattered coherent beam 24 from distal end 23 via reflectors21, 22, by optical fiber 29 in FIG. 3 b, or alternatively by deflectors27 as shown in FIG. 3 c, to site 26 that is to be treated within tissue25. Following the surgery, a well-defined spot is generally producedhaving a size of up to 20 mm, depending on the specific application anddevice. Furthermore, beam 24 may be directed by means of motor 28 asshown in FIG. 3 c in those situations in which extensive surgery isdesired and tissue 25 needs to be scanned. When the wavelength rangesfrom 310-1600 nm, i.e. ultraviolet and near-infrared, the beam isscattered into individual rays 30, as shown in FIG. 3 d, whilepropagating to blood vessel 32 from site 26. Blood vessel 32 ispresented as an example and could be replaced by a hair follicle or anytype of skin lesion. At wavelengths ranging from 1750 nm to 11.5microns, i.e. far infrared, lasers are often used in focused pin-pointablation, that is, having a diameter ranging from 50-200 microns at ashallow depth of 20-150 microns, of epidermal or papillary dermal tissuein conjunction with a scanner, as shown in FIG. 3 e. The lasers are usedmainly for ablation of tissue, the formation of a crater shown in FIG. 3f. Laser 20, which is capable of effecting the desired surgery at alarge distance between distal end 23 and target site 26 for the variousapplications shown in FIGS. 3 a-d, nevertheless can cause severe damageif the beam is not properly aimed.

In contrast, the present invention, which is schematically depicted inFIG. 4, presents a much lower risk to the patient and to observers. Asshown in FIG. 4 a, diffusing unit 15 is attached to distal end 23 of thelaser unit. Diffusing unit 15 transforms the coherent, usuallycollimated laser beam 24 into homogeneous, randomly scattered beam 14shown in FIG. 4 b. As a result beam 14 significantly reduces risk ofinjury to the skin as shown in FIG. 4 c or to the eyes as shown in FIG.4 d since a collimated beam is not directed to these parts of the body.At very short distances of less than one tenth of the diameter of beam24 from distal end 23, beam 24 has not begun to completely scatter andincrease its diameter and is therefore efficacious as a means forperforming cosmetic surgery as shown in FIG. 4 c, although an increasein the laser power level may sometimes be needed to compensate forreverse reflections from the diffusing unit into the laser unit.Compensation, in terms of an increase in the needed power level for thelaser unit, for reverse reflections is usually be close to 16% due tofour air-glass interfaces with 4% Fresnel reflection, and at times mayattain 50%. An anti-reflection coating may be used to reduce reflection.For laser units which operate at approximately 10-20% of their maximumenergy capacity, it is possible to place the exit plane of the diffusingunit, whether a frosted or clear transmitting element, at a distancefrom the skin corresponding to approximately 50% of the exit beamdiameter.

FIG. 5 demonstrates the advantages of the present invention. FIG. 5 aillustrates conventional coherent laser beam 24 at a wavelength of 308to 1600 nm. The collimated beam contacts tissue 25 at a diameter of Dbefore being scattered into individual rays 30 during propagation totarget destination 32. FIG. 5 b illustrates the result of attachingdiffusing unit 15 to the laser unit. When diffusing unit 15 is disposedat a small distance from the tissue surface, the diameter of thescattered beam which contacts tissue 25 is increased by a negligiblevalue of Δd, assuming uniform scattering, in comparison with theoriginal beam diameter of D. If the thickness t of diffusing unit 15 isless than one-tenth of original beam diameter D, there will be a loss ofless than 20 percent in the original beam energy density. Also, therefraction angle θ, corresponding to an index of refraction of 1.5 forkeratin, into the tissue relative to collimated beam 24, when a gapexists between diffusively transmitting element 13 and cleartransmitting element 17, will never exceed the critical angle of 42degrees. At a refraction angle less than this critical value, possibleadditional scattering in tissue is minimized. Consequently lightintensity within the tissue is preserved, therefore generally retainingthe clinical efficacy, i.e. the ability to perform a surgical orcosmetic procedure, of the laser unit.

Just as superficial ablation 29 is formed in tissue 25 as a result of ahigh energy density beam in the 1.8 to 11.5 micrometer spectral range asshown in FIG. 5 c, a similar ablation may be formed in tissue 25 withthe use of diffusing unit 15, with the addition of Δd, as shown in FIG.5 d. A thin spacer (not shown) may be advantageously added in order toevacuate vapors or smoke that has been produced during the vaporizationprocess. Such a spacer is e.g. U-shaped in vertical cross-transmissionelement, to allow for contact with a target at its lateral ends and forvapor evacuation along the gap formed by its central open region. Forsurgical procedures with which a very fast ablation rate is needed, e.g.1 cm³/sec for a skin thickness of 0.1 cm, the spacer is necessarilyrelatively thick and the gap between the ablated tissue and thediffusing unit is relatively large, e.g. approximately 20-30 mm.

When an excessive amount of smoke is produced and the exit beam becomesdiffracted before impinging on the tissue, it may be necessary to add arelay optics device (not shown), which regenerates the degraded exitbeam between the diffusing unit and the tissue. An optical regeneratoris provided with an internal coating, such that a new and stronger beamwith the same characteristics as the degraded beam is produced when thecoating emits light energy when stimulated by the incoming photons ofthe degraded beam. Cylindrical or conical tubes internally coated withgold with an inlet diameter equal to the exit diameter of the diffusingunit are exemplary optical regenerators for this application. A smallsmoke evacuation port is preferably drilled in the wall of the tube.

When a long-wavelength laser, which does not focus on an eye retina andranges from approximately 1345 nm to 10.6 microns, is employed, andiffusing unit may not be needed. To scatter the exit beam, an elementmay be externally attached to a surface which is in contact with theskin during a cosmetic or surgical procedure, so that the exit beam willdiverge to a large extent and ensure eye safety from a distance of a fewcm from a target, while the energy density is sufficiently high enoughto allow for clinical efficacy. For example, a miniature 0.21Joule/pulse Erbium laser, which produces a spot size of 1 mm² andgenerates an energy density of 2.1 J/cm², greater than the threshold fortissue ablation, will be safe to the eyes from a distance of 10 cm froma target if the beam has a divergence half angle of 45 degrees.

While the laser is an effective surgical tool when the diffusing unit isvery close to the tissue surface, safety is ensured after the diffusingunit is repositioned so that it is disposed at a distance of a fewmillimeters, depending on the laser energy, from the tissue surface. Asshown in FIG. 5 e, the energy density of scattered beam 14 whichimpinges upon the surface of tissue 25 is much less than the energydensity which results when the diffusing unit is proximate to the tissuesurface.

The diffusing unit is adapted to induce random scattering despite anyadverse external conditions encountered during the surgical procedure.

The most likely cause of a potential change in rate of scattering of thelaser beam passing through diffusing unit 15 results from contact withtissue. Following a surgical procedure in which the diffusing unitcontacts tissue, liquid residue 36, such as sebum, water and coolinggel, as shown in FIG. 6 a, may accumulate on diffusively transmittingelement 13. The refractive index of liquid residue 36 may be such that,in combination with the refractive index of diffusively transmittingelement 13, refracted beam 38 approaches the pattern of collimated beam24 that impinges on the diffusing unit.

To minimize the risk of injury which may exist if the refracted beam isnearly collithated, diffusively transmitting element 13 is mountedwithin diffusing unit 15, which is preferably hermetically sealed withsealing element 39 as shown in FIG. 6 b, to prevent the accumulation ofliquid residue on the former. Clear transmitting element 42 is attachedto the distal end of diffusing unit 15 by adhesion and by means of aspacer (not shown), and is separated from diffusively transmittingelement 13 by air gap 41. Clear transmitting element 42 and diffusivelytransmitting element 13 are mutually parallel, and both areperpendicular to the longitudinal axis of diffusing unit 15. When theair gap is less than a predetermined value, a corresponding increase inbeam diameter due to scattering is limited, thereby ensuring a minimaleffectiveness of the radiation carried by the laser beam for clinicalapplications. It would be appreciated that accumulation of liquidresidue on clear transmitting element 42 will not compromise theinherent safety of a laser unit equipped with a diffusing unit. Sincescattering occurs at diffusively transmitting element 13, and thecombined index of refraction of air gap 41, clear transmitting element42 and liquid residue is not sufficient to cause the scattered beam tobe once again collimated, the inherent safety of the laser unit ispreserved. The accumulation of liquid residue will not affect theclinical efficacy of the laser unit since clear transmitting element 42is held close to a target during a surgical procedure.

An additional advantage resulting from the separation of cleartransmitting element 32 from diffusively transmitting element 13 relatesto added safety. Even if clear transmitting element 42 is broken,diffusively transmitting element 13 will scatter the laser beam.

A diffusively transmitting element, adapted to achieve diffusing halfangles greater than 45 degrees and as close as possible to an idealtransmitting diffuser, which generates a half angle of 60 degrees, maybe produced in several ways:

-   -   Sandblasting the surface of a plate of glass, sapphire, acrylic        or polycarbonate with fine particles having a size ranging from        1 to 200 microns, depending of the wavelength of the laser beam,        comprised of, by example, aluminum oxide;    -   Sandblasting the surface of a mold plate with fine particles        having a size ranging from 1 to 200 microns, depending on the        wavelength of the laser beam, comprised of, by example, aluminum        oxide and reproducing the contour of the newly formed mold plate        surface by pressing hot acrylic, or other suitable material        thereon;    -   Etching the surface of a glass or sapphire plate by chemical        means, such as with hydrogen fluoride;    -   Etching the surface of a glass plate with a scanned focused CO₂        laser beam;    -   Applying a thin sheet of light-diffusing polymer, such as a        polycarbonate sheet, a light diffusing acrylic plate, Mylar high        quality wax paper or graphical “Pergament Paper” to a glass        plate;    -   Generating a diffraction pattern on the surface of a glass or on        a sheet of acrylic or polycarbonate by means of a holographic        process to thereby control the divergence angle through the        diffraction pattern, which is preferably as large as a half        angle of at least 40-45;    -   Providing a randomly distributed array of thin fibers, arranged        e.g. in the form of a conical fiber bundle light concentrator,        such as that produced by Schott, Germany, whose aperture is        provided with an exit half angle of greater than 40 degrees.

FIG. 7 illustrates the scattering effect that is achieved bysandblasting. As shown in FIG. 7 a, metallic plate 50 is bombarded withaluminum oxide particles 48, thereby creating a random distribution ofcraters 51, each of which having a different size. Liquid 52, which issensitive to ultraviolet light, is spilled on metallic plate 50 in FIG.7 b and polymerized by ultraviolet radiation. After removal of plate 50,for reuse in the next production batch, transparent frosted plate 53 isproduced, as shown in FIG. 7 c covered on one side with a randomdistribution of convex lenses 55 of miniature size. Lenses 55, whichhave a very short focal length of approximately a few wavelengths,convert a collimated laser beam into a strongly divergent beam with acomplete loss of coherence. It is possible to use a similar technique toproduce a surface with convex or concave microlenses 57, as shown inFIG. 7 d. Microlenses may be produced as well by pressing melted acryliconto a multimicrolens mold, instead of using a UV curing technique.

As described above, an exit beam from a laser unit is randomly scatteredby a diffusing unit. One type of a diffusing unit is a single wide anglediffuser as shown in FIG. 8 a and comprises a diffusively transmittingelement 781 which produces scattered light 782 from laser beam 780having a wide diffusing angle of T. Another type of diffusing unit isshown in FIG. 8 b, wherein wide angle diffusion is attained by usingdivergent optical element 783, and at least one diffuser 784 andrefractive/reflective element 785. With this type of diffusing unit, awide diffusing angle of T is generated in three stages: optical element783 produces wide angle divergent beam T₁ from laser beam 780, diffuser784 produces a small diffusing angle of T₂, and refractive/reflectiveelement 785 expands angle T₂ to achieve wide diffusing angle T. Such amulti-component diffusing unit may achieve a wide diffusing angle withthe use of elements of high thermal resistance and durability. It willbe appreciated that refractive/reflective element 785 may notnecessarily be distally disposed with respect to diffuser 784, and maybe configured in any other way in order to achieve wide diffusing angleT.

FIG. 9 illustrates another preferred embodiment of a diffusing unit,designated as numeral 200. Diffusing unit 200 is a wide angle diffusingunit, i.e. one that generates a scattering angle that approaches that ofan ideal transmitting diffuser, yet is capable of enduring high powerlaser levels by using glass made of small angle diffusers. Such adiffusing unit is advantageously employed in those applications forwhich high energy densities are needed for clinical efficacy, andaccordingly only a wide-angle scattering angle can ensure eye safety.

As depicted in FIG. 9 a, optic fiber 201 is disposed adjacent to theproximate end of tapered light guide 202, such that light rays 203 thatexit from fiber 201 with half angle divergence A impinge the inner wallof light guide 202. Rays 203 then are reflected from the inner wall ofthe light guide at an increasingly smaller reflection angle R. The innerwall is coated with a reflective coating so that reflection angle R willbe less than the critical angle for total internal reflection. Thetapering angle and the dimensions of the light guide as well as thedistance of the fiber from the light guide are selected so that exithalf angle C of diffused light 208 which propagates from distal end 204of the light guide is at least 60 degrees. Also, the distance betweenfiber 201 and distal end 204 is selected so that the energy density ofrays 207 emitted from fiber 202 to distal end 204 without any reflectionfrom the light guide wall will be sufficiently low to be considered evesafe when scattered from small angle diffuser 205, e.g. 10 degrees,which induces a relatively small scattering angle and is proximatelyplaced with respect to distal end 204 of the light guide. A small anglediffuser is advantageously selected due the availability of suchdiffusers, its high durability and capability to withstand a high energydensity, as required for aesthetic and industrial applications. Smallangle diffuser 205 increases the divergence of difused light 208, inaddition to the divergence generated by tapered light guide 202.

In an exemplary diffusing unit, fiber 201 induces a half angledivergence of 25 degrees, the distance from fiber 201 to light guide 202is 16 mm, the inner diameter of light guide 202 at its proximate end is15 mm, the tapering angle of light guide 202 is 3 degrees, and thelength of light guide 202 is 142 mm.

Diffusing unit 200 may also include a second light guide (not shown)which receives diffused light 208 from the distal end of light guide202. This second light guide is sufficiently long so that diffused light208, which propagates from small angle diffuser 205, will be emittedfrom the entire surface of the exit plane of the second light guide. Theexit plane of the second light guide therefore functions as an extendeddiffused source. For example, a second light guide having a length of 50mm and a small angle diffuser which induces a scattering angle of 10degrees will enable diffused light to span a diameter of greater than 5mm at the exit of the second light guide.

As shown in FIG. 9 b, diffusing unit 200 comprises array of microlenses210, instead of an optic fiber as in FIG. 8 a, which is disposedadjacent to the proximate end of tapered light guide 202. Array 210 isconfigured such that light rays 203 that exit therefrom with half angledivergence A impinge the inner wall of light guide 202.

FIG. 10 illustrates diffusing unit 700, which comprises another type ofangular beam expander, namely one which comprises a set of concave andconvex mirrors. Small angle fiber 701 from which light rays 703 exitwith a small half angle divergence A, such as 5 degrees, isadvantageously employed since diffuser unit 700 provides a high angularamplification.

As shown in FIG. 10 a, half angle divergence A is selected so that alight ray 703 impinges on convex mirror 702 and is reflected therefromto concave mirror 705. A ray 703 is further reflected from mirror 705 atan angle that enables it to impinge upon, and be scattered by,diffusively transmitting element 710, which is affixed to concave mirror705. In FIG. 10 b, diffuser unit 700 is additionally provided with lightguide 715. The light which exits from diffusively transmitting element710 is received by light guide 715 and is reflected within its innerwall, resulting in wide angle diffusing from the entire exit surface oflight guide 715. Light guide 715 therefore functions as an idealextended diffused light source.

FIG. 11 illustrates a diffuser unit in which two 40.45 degreesholographic diffusers 220 and 221 are attached to light guides 222 and223, respectively. Each holographic diffuser induces a half angledivergence of approximately 45-50 degrees. In order to increase thedivergence, two holographic diffusers are used. Light rays 218propagating from a monochromatic light source are scattered by diffuser220 to a half angle of D and then are reflected within the inner wall oflight guide 222. The scattered light rays are further scattered bydiffuser 221 to a half angle of E, are reflected within light guide 223,and exit the diffuser unit at a half angle of F, which approaches 60degree, the value corresponding to an ideal transmitting diffuser. Thelight guides are chilled so that the holographic diffusers, which areusually made from plastic material, will also be chilled so that theywill be able to withstand the high thermal stress imposed by a highpower laser beam. Each light guide may be solid or hollow, and may bemade from glass, sapphire, a liquid dielectric, or plastic.

FIG. 12 illustrates another preferred embodiment of the invention inwhich diffuser unit 300 comprises two distinct diffusers 301 and 302,wherein at least one is axially displaceable. FIG. 12 a illustratesdiffuser unit 300 in an active position, such that diffusers 301 and 302are essentially in contact with each other. When in an active position,diffusers 301 and 302 act as a singular randomly scattering diffuser,since substantially all of the monochromatic light 305 that impinges ondiffuser 301 is transmitted to diffuser 302. Although the energy densityneeded for performing an efficacious treatment with monochromatic light305 is minimally affected, a slight increase of the laser energy cancompensate for any energy density losses. FIG. 12 b illustrates diffuserunit 300 in an inactive position, such that diffusers 301 and 302 areseparated from each other by a distance L, which is sufficiently long toensure that the radiance of the scattered light which exits diffuser 301and is additionally scattered by diffuser 302 is below a level that issafe to one's eyes.

As shown, diffuser 301 is axially displaceable by means of a pluralityof springs 308 that connect diffuser mount 301 a to diffuser mount 302a. When lever 315, which is connected to diffuser mount 301 a, isdepressed springs 308 are compressed and diffuser 301 becomessubstantially in contact with diffuser 302, as shown in FIG. 12 a.Distal end 317 of handpiece 303 is then brought in contact with a skinlocation to be treated by monochromatic light 305 having a high energydensity and a high radiance. Upon completion of a desired surgical orcosmetic procedure, lever 315 is released and springs 308 are biased toseparate diffuser 301 from diffuser 302 by a distance of L, as shown inFIG. 12 b, whereby the radiance of the scattered light is below a safelevel. It will be appreciated that any other means well known to thoseskilled in the art for axially displacing one or more of the diffusersmay be used.

FIG. 13 illustrates an embodiment of the present invention by whichtissue, having a larger surface area than the area of the beam impingingthereon, may be treated without overexposure to a laser beam. In priorart systems using a scanner, the treatment beam is quickly displaced ina programmable fashion from one location to another on the tissue to betreated. Although this method provides rapid and reliable treatment,there is a significant risk, however, that the laser beam is liable tobe aimed at eyes, skin or flammable materials located in the vicinity ofthe laser unit.

The diffusing unit generally designated by 60 is shown. In thisembodiment the diffusing unit is rigidly attached to delivery system 61,which is provided with a scanner. Diffusively transmitting element 63 isformed with a plurality of visible targets 66 and is placed close to theskin, facing the distal end of delivery system 61. Diffusing unit 60 ispreferably provided with a clear transmitting element, as describedhereinabove. Coherent collimated or convergent exit beam 64 is directedvia a plurality of repositionable reflectors 65 to a predeterminedtarget 66 graphically indicated on diffusively transmitting element 63.The beam that impinges upon a predetermined target 66 is randomlyscattered and converted into non-coherent beam 67 whose energy densityis essentially similar to that of exit beam 64. Reflectors 65 arecontrollably repositionable by means of a scanner, whereby they may bedisplaced from one position and angular disposition to another, so as toaccurately direct exit beam 64 to another target 66. The sequence ofwhich target is to receive exit beam 64 after a selected target isprogrammable and is preferably semi-random to reduce pain which may befelt resulting from the treatment of two adjacent targets, with the timeincrement between two doses of laser treatment being less that less thana preferred value. A programmable sequence precludes on one hand thechance of a target not to receive an exit beam at all, and on the otherhand precludes the chance of not to be inadvertently exposed twice tothe exit beam. With the usage of diffusing unit 60, small-diameterbeams, e.g. 0.1-7.0 mm, may be advantageously employed to treat a tissuehaving an area of 16 cm². Similarly, a scanner may be employed for anyother feasible wide-area diffusing unit, such as an array ofdiffusers/light guides incorporating those units illustrated in FIGS.9-12, whereby an exit laser beam may be directed to each of thediffusers/light guides. Such an array may consist of 9 diffuser/lightguides, each having a 3-mm diameter, to cover an area of 81 mm².Scanning may also be achieved by laterally moving an angular expanderover the diffuser/light guide array.

FIG. 14 illustrates another preferred embodiment of the invention inwhich a diffusing unit is not used, but rather a diverging opticalelement is employed to produce an exit beam having radiance, oralternatively, energy density, depending on the wavelength, below a safelevel.

As shown in FIG. 14 a, diverging optical element 741 is placed indiverging unit 748, which is attached to the distal end of the laserunit by any means depicted hereinabove in FIG. 2. Divergent element 741,which is provided with a relatively short focal length, focuses inputbeam 740 at point F. The beam diverges at a point distally located withrespect to point F, as well known to those skilled in the art, andproduces divergent beam 742 having a divergent angle of H, a crosssection 743 at a plane coplanar with distal end 744 of diverging unit748 and a cross section 752 at a plane coplanar with shield 750. Whendivergent beam 742 has a cross sectional dimension at least equal tocross section 752, its radiance is less than an eye safe level.

Pulsed laser radiation in the wavelength range of 1400 nm to 13 microns,according to the ANSI Z 136.1 standard, is considered eye safe if theAccessible Energy Limit (AEL) at the ocular plane is less than a valueof 0.56*t**(¼) J/cm², where t is the pulse duration in seconds. Forexample, a typical pulse duration ranging from 1 to 100 msec isassociated with an AEL ranging from 0.1 to 0.3 J/cm², respectively.Accordingly, diverging unit 748 is provided with at least one shield750, each of which prevents one's head from entering a zone of thedivergent beam at which the energy density is greater than the AEL.Shield 750 is connected to tube 746 of diverging unit 748 by means ofrigid member 747, and cross member 749. The length of cross member 749and the degree of angular divergence H is selected to ensure that theenergy density distal to shield 750 is less than the AEL. Normally,cross member 747 is unyielding to head pressure, thereby ensuring eyesafety. However, when a lever is actuated, for example, cross member 747is opened and a spring (not shown), which is normally in a relaxed stateand connected to both rigid member 747 and cross member 749, becomestensed and allows the shield to be proximately displaced. When shield750 is proximately displaced, distal end 744 of diverging unit 748 maybe in contact with a target skin location and cross section 743 of beam742 having a sufficiently high energy density for a desired applicationmay be utilized. For example, diverging unit 748 is suitable for thoseapplications by which a laser beam is greatly absorbed by water.

FIG. 14 b illustrates diverging unit 950, which comprises array 991 offocusing lenslets each of which has a diameter of e.g. 0.7 mm, array 992of lenses each of which is provided with reflective coating 993 on itsdistal side, and a plurality of convex reflectors 995 attached totransparent plate 994. Rays 990 from a collimated laser beam are focusedby lenslets 991 and transmitted through non-reflective area 999 formedon the distal side of each lens 992. The location of each non-reflectivearea 999 is selected so that a focused ray propagating therethrough willimpinge upon a corresponding reflector 995 at such a reflecting anglesuch that it will be reflected therefrom and strike a correspondingreflective coating 993, from which it is again reflected and propagatesthrough transparent plate 994. Most rays, such as ray 996 then exitplate 994. However, some rays, such as ray 989, strike a transversalside 997 of plate 994, which is provided with a reflective coating andcauses these rays to exit plate 994. Plate 994 accordingly functions asa light guide when transversally reflecting light rays strike a side997. The length, i.e. the distance between sides 997, of plate 994 issubstantially equal to the length of array 991, and therefore the energydensity of an input beam is preserved at the exit of plate 994. In orderto comply with the requirements of the aforementioned standards, namelyto achieve a safe radiance level with a lens having a diameter of 0.7 mmand producing a divergent half angle of 60 degrees, a lenslet 991 with afocal length of 3 mm may be used to achieve a uniform radiance at asolid angle of approximately Π steradians.

The distal end of plate 994 may be etched to further diffuse thedivergent light exiting therefrom, so that the distal end may functionas an extended diffused light source. If desired, the transparent platemay be substituted by a light guide.

In summation, the present invention incorporates four groups of unitswhich cause a monochromatic light to diverge at a sufficiently wideangle so that the radiance of an exit beam is eye safe:

1) A diverging unit provided with a single diverging optical element;

2) A multi-component diverging unit provided with reflective andrefractive optical elements, and without any diffusers;

3) A diffusing unit provided with a single thin diffusively transmittingelement; and

4) A multi-component diffusing unit, whereby a wide divergent, diffusingangle is achieved by using a high thermally resistantrefractive/reflective optical component, as well as at least onethermally resistant low angle diffuser.

When a multi-component diffusing or diverging unit is employed, arelatively simple eye safety monitoring device can be used. Due to thehigh thermal durability of the selected multi-component unit, theradiance homogeneity is essentially preserved from the proximate end tothe distal end thereof. Consequently, limited sampling of the radiancelevel is required, and an expensive monitoring device is renderedunnecessary. Another advantage of a multi-component unit is thatmonochromatic light reflected from the skin returns to the correspondingunit via a light guide with respect to a diffusing unit and via atransparent plate with respect to a diverging unit, preventing anadverse effect to the skin if reflected monochromatic light were toreturn thereto.

FIG. 15 illustrates another preferred embodiment of the invention inwhich a diffusing unit is provided with a skin cooling system.Transparent skin cooling devices are often used in conjunction with skinlaser treatments. However they do not scatter laser light and do notreduce the risks associated with exposure to a laser beam. FIGS. 13 a-dillustrate prior art skin coolers. In FIGS. 15 a and 15 b transparentlenses or plates 80 are in contact with tissue 79. Cooling liquid 81,which flows through conduit 83, conducts heat from the heated skin to acooler. Treatment laser beam 82 propagates without being scatteredthrough the cooling device and penetrates the skin. In FIG. 15 c gaseouscoolant 84 is used. In FIG. 15 d, highly conductive plate 86 is incontact with tissue 79 and chilled by thermoelectric cooler 85.

As shown in FIG. 15 e, diffusing unit 75 comprises diffusivelytransmitting element 74, clear transmitting element 70 and conduit 71formed therebetween. Conduit 71 is filled with a low temperature gas orliquid of approximately 4° C., which enters conduit 71 through opening72 and exits at opening 73. The cooling fluid preferably flows through acooler (not shown). Diffusing unit 75 is positioned in contact with theskin, for treatment and cooling thereof. Clear transmitting element 70is preferably produced from a material with a high thermal conductivitysuch as sapphire, in order to maximize cooling of the epidermis.Diffusively transmitting element 74 is disposed such that its proximalface is frosted side and its distal face is planar, facing conduit 71.In FIG. 15 f, the diffusing unit comprises diffusively transmittingelement 74 made from sapphire, which is chilled at its lateral sides 75by thermoelectric cooler 76. The proximal side of 74 is frosted and thesmooth distal side faces the skin. The parameters of the flowing fluidand of the cooler are similar, by example, to the Cryo 5 skin chillerproduced by Zimmer, Calif., USA. It will be appreciated that any of theskin cooling means illustrated in FIGS. 15 d-f may be used to cool skinwhich is heated as a result of the impingement of monochromatic lightthereon even though a diffusively transmitting element is not used.

The eye safety when exposed to the exit beam of a diffusing or divergingunit is significantly improved relative to prior art devices.

Parameters for eye safety analysis are presented in “Laser SafetyHandbook,” Mallow and Chabot, 1978 in which the standard ANSI Z 136.1 iscited. A laser beam which is reflected from a light diffusing surface iscategorized as an extended diffused source if it may be viewed at adirect viewing angle A, greater than a minimum angle Amin, with respectto a direction perpendicular to the source of the laser beam. If areflected beam may not be viewed at angle A, it is categorized as anintrabeam viewing source. Since a reflected beam is more collimated whenviewed at a distance, viewing conditions are intrabeam if the distance Rfrom the source of the laser is greater than a distance Rmax.

Another significant parameter is the maximum permitted radiance,normally referred to as Accessible Energy Limit (AEL) while staring at adiffusing surface which completely reflects a laser beam. AEL depends onthe energy density, exposure duration, and wavelength of the laser beam,as well as the solid angle into which the laser beam is diffused. Thesafety level of a laser unit is evaluated by comparing the AEL to theactual radiance (AR) of the laser beam. Staring at the exit of adiffusing unit according to the present invention is equivalent tostaring at a reflecting extended diffuser with 100% reflectivity. TheAEL for visible and near infrared radiation exiting a diffusing unit forwhich protective eyeglasses are unnecessary based on an extendeddiffuser source is defined by ANSI Z 136.1, as 10*k1*k2*(t^⅓) J/cm²/sr,where t is in seconds and k1=k2=1 for a wavelength of 400-700 nm,k1=1.25 and k2=1 at 750 nm, k1=1.6 and k2=1 at 810 nm, k1=3 and k2=1 at940 nm and k1=5 and k2=1 at a wavelength of 1060 to 1400 mm. The safetylimit set by ISO 15004: 1997 E for pulsed radiation is 14 J/cm²/sr.

The actual radiance (AR) is the actual energy per cm² per steradianemitted from a diffusing unit. The ratio between AEL and AR indicatesthe safety level of the laser unit employing a diffusing unit, accordingto the present invention. A ratio less than 1 is essentially unsafe. Aratio between 1.0 and 5 is similar to that of high intensity flashlightsources used in professional photography and intense pulsed lightsources used in aesthetic treatments, and is much safer than prior artlaser sources. Prior art laser sources which do not incorporate adiffusing unit have a ratio which is several orders of magnitudes lessthan 1.

Table I below presents a comparison in terms of eye safety between theexit beam of monochromatic light after being scattered by a diffusingunit into a solid angle of 3.14 sr, which is equivalent to that attainedby an ideal transmitting diffuser, according to the present invention.The parameters for a non-coherent diode-based laser unit are based onone produced by Dornier Germany. The parameters for a non-coherentAlexandrite-based laser unit are based on one produced by Sharplan/ESC(Epitouch). The parameters for a non-coherent Nd:YAG-based laser unitintended for hair removal are based on one produced by Altus, USA. Theparameters for a non-coherent Nd:YAG-based laser unit intended forphoto-rejuvenation are based on one produced by Cooltouch, USA. Theparameters for a non-coherent dye-based laser unit are based on oneproduced by ICN (Nlight). The parameters for an intense pulsed lightlaser unit are based on one produced by ESC. The AEL for a particularwavelength and pulse duration is based on the aforementioned ANSI Z136.1 standard.

TABLE I Non coherent Non coherent Non coherent CW Diode Non coherentAlexandrite Nd: YAG Nd: YAG Non coherent Intense Pulsed 60 degreesSystem type Diode based based based based Dye based Light diffuserApplication Hair removal Hair removal Hair removal Photo- Photo- Hairremoval Tooth re juvenation re juvenation whitening ParametersWavelength 940 nm 755 nm 1064 nm 1320 nm 585 nm 645-900 nm 980 nm Energy6 J 10 J 11.3 J 7 J 0.6 J 90 J 1.5 J Pulse duration 50 msec 40 msec 60msec 60 msec 0.5 msec 40 msec 1 sec Spot size 5 mm 7 mm 6 mm 6 mm 5 mm10 × 30 mm² 5 × 5 mm² Energy density 30 J/cm² 25 J/cm² 40 J/cm² 25 J/cm²3 J/cm² 30 J/cm² 6 J/cm² Extended view parameters A min 8 mrad 3.5 mrad4 mrad 4 mrad 2.5 mrad 5 mrad 15 mrad R max 0.4 m 2 m 2 m 2 m 1.3 m 4 m0.33 m Eye safety Parameters AEL/sr 11 J/cm²/sr 4.3 J/cm²/sr 19.5J/cm²/sr 20 J/cm²/sr 0.79 J/cm²/sr 3.4 J/cm²/sr 35 J/cm²/sr AR/sr 9.6J/cm²/sr 8 J/cm²/sr 12.7 J/cm²/sr 8 J/cm²/sr 0.79 J/cm²/sr 9.5 J/cm²/sr8 J/cm²/sr Eye safety 1.14 0.53 1.54 2.5 1 0.35 4.1 Figure of meritAEL/AR

The table shows that the exit beam according to the present invention isessentially as eye-safe, or safer than, broad band non-coherent intensepulsed light sources, such as those used for professional photography orthose used for cosmetic surgery. The scattered monochromatic light, formost of the light sources, does not necessitate protective eyeglassesand is safer than an accidental glance into the sun for a fraction of asecond. Although the ratio for the Alexandrite and Intense Pulsed Lightsources is less than 1 and protective eyeglasses must be worn, therequired optical attenuation for these light sources is less than 3,much less than the required optical attenuation with the use of aconventional monochromatic light source not provided with a diffusingunit, which is on the order of 10⁴·10⁷. It will be appreciated that asimilar level of eye safety for laser units utilizing a diffusing unitmay be achieved with a very wide scattering angle, approaching a halfangle of 60 degrees or a solid angle of Π steradians. Small anglescattering may result in a different level of eye safety when operatedat an energy density suitable for aesthetic treatments; nevertheless,such a scattered exit beam is much safer than the exit beam of aconventional coherent laser unit.

The radiance of the light emitted by a diffusing unit can be measured toverify that it is in compliance with the appropriate standards for lasereye safety. In one embodiment, a converted laser utilizing a diffusingunit in accordance with the present invention is provided with an eyesafety measurement device. Such a device may be an energy meter such asthat produced by Ophir, USA or an array of light detectors 805 asdepicted in FIG. 16. The eye safety measurement device is provided withcontrol circuitry which is in communication with the operating system ofthe laser unit, so that, as a result of a mishap, a warning is issuedindicating that protective eyeglasses are required if the measuredradiance of a scattered laser beam is greater than a predetermined safevalue. Alternatively, the control circuitry may discontinue operation ofthe laser unit if the measured radiance of a scattered laser beam isgreater than a predetermined safe value.

FIG. 16 illustrates an exemplary eye safety measurement device,designated as numeral 800. Device 800 is operative to measure theradiance of scattered light 810, which is scattered by means ofdiffusing unit 15 attached to distal end 809 of laser unit handpiece801. Device 800 is provided with an array of light detectors 806, e.g.complementary metal oxide semiconductor (CMOS) detectors which providelight imaging, at distal end 805 thereof, on which scattered light 810impinges after passing through aperture 808 of diameter Q₀ and lens 807.After distal end 809 is inserted into a complementary opening formedwithin device 800 until contacting annular abutment plate 804perpendicular to outer wall 803 of device 800, the laser unit is fired.For purposes of clarity, light which propagates through segment Q₁ ofdiffusing unit 15 impinges on segment Q₂ of detector array 806. Theradiance of scattered light 810 therefore is determined by dividing theamount of energy sensed by detectors 806 by diameter Q₀ of aperture 808and by the solid angle characteristic of the detector structure. Forexample, the distance D between abutment plate 804 and aperture 808 is200 mm, segment Q_(i) of the diffusing element 15 is 0.7 mm, anddiameter Q₀ of the aperture is 7 mm, to comply with the regulations setforth in ANSI Z 136.1.

FIG. 17 illustrates another embodiment of the invention, wherein eyesafety in the vicinity of a laser unit that emits an infrared beam orother invisible radiation is increased by adding a flashing device tothe laser system to cause one's eyes to blink during the propagation ofthe laser beam.

FIG. 17 a illustrates distal end 960 of a laser unit, which emits light955 generated therefrom, preferably being scattered monochromatic lightwhen a diffusing unit is employed. To prevent damage to eye 962 of abystander located in the vicinity of the laser unit, flashing device 961is added to distal end 960. Flashing device 961 generates a shortvisible light flash a fraction of a second prior to the firing of alaser beam.

As shown in FIG. 17 b, activation of the laser unit initiates anelectrical pulse 963 at time to, which triggers a timer circuit (notshown). The timing circuit is adapted to generate and transmit pulse 964at time t₁ to flashing device 961, to produce a flash is sensed by eye962. Flashing device 961 may be a well known flashing means associatedwith cameras or may utilize diodes, or any other feasible means toproduce an instantaneous flash. After a predetermined period of time,the timing circuit transmits a pulse to the control system of the laserunit to fire a laser beam at time t₂. This predetermined period of time,namely the difference between t₂ and t₁, is approximately 0.25 seconds,equal to the reaction time of uncontrolled blinking as a response tolight, and is preferably no more than 0.20 seconds. A flashing device961 may be added to any source of monochromatic light, such as any typeof laser or IPL sources, whether producing visible or invisible light.

FIG. 17 c illustrates another application of flashing device 961. Bygenerating a flash with device 961 and determining whether detector 975senses light retroreflected from eye 962, a microprocessor (not shown)in communication with a control circuit (not shown) and with detector975, e.g. a photodetector, can determine that eye 962 is in danger ofbeing injured from the imminent firing of a laser beam from the laserunit. The choroid layer of the retina diffusely reflects light source973 that impinges thereon from the previously generated flash, and theoptics of eye 962, re-image, or retroreflect, the light back to flashingdevice 961. Retroreflected beam 974 is reflected from beam splitter 970through a lens (not shown) onto 975. Two additional adjacent detectors(not shown) detect light reflected from other areas in the room in whichthe laser unit is disposed. If the signal generated by detector 975 hasa much larger amplitude than the signals generated by the additionaldetectors, the microprocessor determines that eye 962 is in firing rangeof a laser beam. The control circuit of flashing device 961then sends adisabling signal to the control system of the laser unit to therebyprevent firing of a laser unit. When detector 975 is used to detect aretroflected beam, and a flash is generated within the predeterminedtime before the firing of a laser beam, as illustrated in FIG. 17 b, inorder to cause uncontrollable blinking of the eye during propagation ofthe beam, the laser unit is inherently fail-safe. That is to say, evenif the eye does not blink, detector 975 will determine that eye 962 isin firing range of a laser beam and the laser unit will cease operation.

As can be seen from the above description, a diffusing/diverging unit ofthe present invention, which is mounted to the exit aperture of aconventional laser unit, induces the exit beam to be divergent/ and orscattered at a wide angle. As a result the exit beam is not injurious tothe eyes and skin of observers, as well as to objects located in thevicinity of the target. Nevertheless, the exit beam generally retains asimilar level of energy density as the beam generated from the exitaperture when the diffusing unit is very close or essentially in contactwith the target, and is therefore capable of performing various types oftreatment, both for cosmetic surgery and for industrial applications.Protective eyeglasses are generally not needed, and if they are needed,conventional sunglasses would be the only requirement, thereby allowingwork in an aesthetic clinic to be less cumbersome.

In another embodiment of the invention, the apparatus is provided with aunit for evacuating vapors, such as condensed vapors that were producedduring the chilling of skin prior to the firing of the laser unit. Theevacuation unit comprises a U-shaped vacuum chamber through whichmonochromatic light passes as it is directed to a skin target and avacuum pump. During operation of the vacuum pump, the vacuum levelwithin the vacuum chamber is increased by occluding a conduit of thevacuum chamber by a finger of the operator. As vacuum is applied to theskin target, skin is drawn toward the vacuum chamber and theconcentration of blood vessels in the vicinity of the target increases.The added concentration of blood vessels increases the absorption oflight within the tissue, and therefore facilitates treatment of a skindisorder.

FIG. 18 illustrates the propagation of an intense pulsed laser beam thewavelength of which is in the visible or near infrared region of thespectrum, i.e. shorter than 1800 nm, from the distal end of a handpieceto a skin target according to a prior art method. Handpiece 1001comprises clear transmitting element 1002, such as a lens or a window,which transmits monochromatic beam 1007 emitted from the laser unit andimpinges skin target 1004. The beam penetrates skin target 1004 andselectively impinges a subcutaneous skin structure to be thermallyinjured, such as collagen bundle 1005, blood vessel 1009, or hairfollicle 1006. In this method, external pressure or vacuum is notapplied to the skin.

FIG. 19 illustrates a prior art non-coherent intense pulsed light systemfrom which light is fired to a skin target for e.g. treatment ofvascular lesions, hair removal, or photorejuvenation. Handpiece 1010comprises light guide 1011 which is in contact with skin target 1004.Beam 1012, which is generated by lamp 1013 and reflected from reflector1014, is non-coherent and further reflected by the light guide walls. Insome handpieces, such as those produced by Deka (Italy), a cleartransmitting element is utilized, rather than a light guide. Chillinggel is often applied to the skin when such a light system is employed.In this method, external pressure or vacuum is not applied to the skin,and the handpiece is gently placed on the skin target, so as to avoidremoval of the gel layer, the thickness of which is desired to remain atapproximately 0.5 mm.

FIG. 20 illustrates a prior art laser system similar to those of U.S.Pat. Nos. 5,595,568 and 5,735,844, which employs an optical component1022 at the distal end thereof in contact with skin target 1004.Pressure is applied to skin target 1004, in order to expel blood fromthose portions of blood vessels 1025, as schematically illustrated bythe arrows, which are in the optical path of subcutaneously scatteredlight, thereby allowing more monochromatic light to impinge hairfollicle 1006 or collagen bundle 1005. Concerning hair removal, melaninis generally utilized as an absorbing chromophore.

FIG. 21 illustrates a prior art device 1031, such as that produced byLPG (France), which is in pressing contact with skin 1033 in order toperform a deep massage of cellulite adipose layer 1037. Device 1031 isformed with a convex surface 1039 in a central region of its planar skincontacting surface 1043. Device 1031 stimulates the flow of lymphaticfluids in their natural flow direction 1038 in order to remove toxicmaterials from the adjoining tissue. The stimulation of lymphatic fluidflow is achieved by applying a vacuum to the interior of device 1031 sothat air is sucked therefrom in the direction of arrow 1034 of the skin.The application of the vacuum draws skin toward convex surface 1039 andinduces the temporary formation of skin fold 1040, which is raised inrespect to adjoining skin 1033. Due to the elasticity of skin, skin fold1040 returns to its original configuration, similar to the adjoiningskin, upon subsequent movement of device 1031, while another skin foldis formed. As device 1031 is moved by hand 1036 of a masseur indirection 1044 of the device, similar to natural flow direction 1038 thelymphatic fluids flow in their natural flow direction. However, thelymphatic fluids will not flow if device 1031 were moved in a directionopposite to direction 1044. Wheels 1035 enable constant movement ofdevice 1031.

In some cellulite massage devices, such as those produced by Deka(Italy) or the Lumicell Touch (USA), a low power continuous workinginfrared light source with a power level of 0.1-2 W/cm² provides deepheating of the cellulite area and additional stimulation of lymphaticflow. Such a light source is incapable of varying the temperature bymore than 2-3° C., since higher temperatures would be injurious to thetissue and cause hyperthermia. Consequently these massage devices areunable to attain the temperatures necessary for achieving selectivethermal injury of blood vessels, hair follicles or for the smootheningof fine wrinkles. Due to the movement of the device, the amount ofoptical energy, e.g. by means of an optical meter, to be applied to theskin cannot be accurately determined.

FIG. 22 illustrates a prior art hair removal device, similar to thedevice of U.S. Pat. No. 5,735,844, which is provided with a slot 1052within a central region of skin contacting surface 1051 of handpiece1050. When handpiece 1050 is placed on skin surface 1058 and a vacuum isapplied to the handpiece via opening 1053, skin fold 1054 is formed. Anarrow slot 1052 induces formation of a correspondingly longer skin fold1054. Optical radiation is transmitted to the two opposed sides 1056 ofskin fold 1054 by a corresponding optical fiber 1055 and optical element1057. Upon application of the vacuum, skin fold 1054 is squeezed toprevent blood flow therethrough. This device is therefore intended toreduce the concentration of blood within skin fold 1054, in order toincrease illumination of melanin-rich hair shafts, in contrast with theapparatus of this embodiment by which blood concentration is increasedwithin the slight vacuum-induced skin protrusion so as to induceincreased light absorption, as will be described hereinafter.Furthermore, this prior art device, due to the reduced concentration ofblood within skin fold 1054, is not suitable for treatment of vascularlesions, photorejuvination, or the method of hair removal which is aidedby the absorption of optical energy by blood vessels that surround orunderly hair follicles (as opposed to the method of hair removal whichis aided by the absorption of optical energy by melanin.

FIG. 23 illustrates the apparatus according to an embodiment of theinvention, which is generally designated by numeral 1070. Apparatus 1070comprises monochromatic light source 1071, handpiece 1073 provided withclear transmitting element 1076 at its distal end, and an evacuationunit which is designated by numeral 1090.

Evacuation unit 1090 comprises vacuum pump 1080, vacuum chamber C, andconduits 1078 and 1079 in communication with chamber C. Vacuum chamberC, which is placed on skin surface 1075, is formed with an aperture (notshown) on its distal end and is provided with a clear transmittingelement 1076 on its proximate end. Vacuum chamber C is integrally formedwith handpiece 1073, such that cylindrical wall 1091 is common to bothhandpiece 1074 and vacuum chamber C. Element 1076 is transparent to beam1074 of intense pulsed light which is directed to skin target T. Element1076 is positioned such that beam 1074 is transmitted in a directionsubstantially normal to skin surface 1075 adjoining skin target T. Theratio of the maximum length to maximum width of the opening, which maybe square, rectangular, circular, or any other desired shape, rangesfrom approximately 1 to 4. Since the aperture is formed with such aratio, skin target T is proximately drawn, e.g. 1 mm from skin surface1075, and is slightly deformed, as indicated by numeral 1087, whileincreasing the concentration of blood in skin target T. Likewise,employment of an aperture with such a ratio precludes formation of avacuum-induced skin fold, which has been achieved heretofore in theprior art and which would reduce the concentration of blood in skintarget T.

Wall 1091 is formed with openings 1077 and 1084 in communication withconduits 1078 and 1079, respectively. The two conduits have a horizontalportion adjacent to the corresponding opening, a vertical portion, and along discharge portion. Openings 1077 and 1084 are sealed with acorresponding sealing element 1093, to prevent seepage of fluid from thevacuum chamber. Conduit 1079 is also in communication with vacuum pump1080, which draws fluid, e.g. air, thereto at subatmospheric pressures.U-shaped vacuum chamber C is therefore defined by clear transmittingelement 1076 of the handpiece, slightly deformed skin surface 1087, wall1091 and conduits 1078 and 1079.

A suitable light source is a pulsed dye laser unit, e.g. produced byCandela or Cynosure, for the treatment of vascular lesions, which emitslight having a wavelength of approximately 585 nm, a pulse duration ofapproximately 0.5 microseconds and an energy density level of 10 J/cm².Similarly any other suitable high intensity pulsed laser unit, such as aNd:YAG, pulsed diode, Alexandrite, Ruby or frequency doubled laser,operating in the visible or near infrared region of the spectrum may beemployed. Similarly, a laser unit generating trains of pulses, such asthe Cynosure Alexandrite laser, the Lumenis “Quatim” IPL or Deka“Silkapill”. The emitted light is transmitted via optical fiber 1072 tohandpiece 1073. Handpiece 1073 is positioned such that cleartransmitting element 1076 faces skin surface 1087. Beam 1074 propagatingtowards slightly protruded skin surface 1087 is substantially normal toskin surface 1075.

Following operation of vacuum pump 1080, air begins to become evacuatedfrom vacuum chamber C via conduit 1079. Occluding conduit 1078, such asby placing finger 1083 of an operator on its outer opening increases thelevel of the vacuum within chamber C to a pressure ranging from 200 to1000 millibar. The application of such a vacuum slightly draws skintarget T towards chamber C without being pressed, as has been practicedheretofore in the prior art, thereby increased the concentration ofblood vessels within skin target T. The efficacy of a laser unit interms of treatment of vascular lesions is generally greater than that ofthe prior art, due to the larger concentration of blood vessels in skintarget T, resulting in greater absorption of the optical energy of beam1074 within bodily tissue.

The operator may fire the laser following application of the vacuum andthe subsequent change in color of skin target T to a reddish hue, whichindicates that the skin is rich in blood vessels. The time delay betweenthe application of the vacuum and the firing, of the laser is based onclinical experience or on visual inspection of the tissue color.

FIG. 24 illustrates another embodiment of the present invention whereinthe operation of the vacuum pump and the pulsed laser unit areelectronically controlled. The depth of light penetration within thetissue may be controlled by controlling the time delay betweenapplication of the vacuum and the firing of the pulsed laser. If thetime delay is relatively short, e.g. 10 msec, blood vessel enrichmentwill occur only close to the surface of the skin at a depth ofapproximately 0.2 mm, while if the delay is approximately 300 msec, theblood vessel enrichment depth may be as great as 0.5-1.0 mm.

Apparatus 1170 comprises handpiece 1101, laser system 1116, evacuationunit 1190 and control unit 1119.

Laser system 1116 includes a power supply (not shown), a lightgeneration unit (not shown), and power or energy detector 1130 forverifying that the predetermined energy density value is applied to theskin target. Handpiece 1101 held by the hand of the operator is providedwith lens 1104, which directs monochromatic beam 1105 transmitted byoptical fiber 1103 from laser system 1116 to skin target area 1140.Clear transmitting element 1100 defining vacuum chamber 1106 isgenerally in close proximity to skin surface 1142, at a typicalseparation H of 1.2 mm and ranging from 0.5 to 4 mm, depending on thediameter of the handpiece. The separation is sufficiently large to allowfor the generation of a vacuum within chamber 1106, but less thanapproximately one-half the diameter of the window 1100, in order tolimit the protrusion of skin target 1140 from the adjoining skin surface1142. By limiting the separation of element 1100 from skin surface 1142while maintaining the vacuum applied to skin target 1140, formation of askin fold is precluded while more blood may be accumulated in a smallerskin thickness. Therefore a significant local rise in the temperature ofa blood vessel, which ranges from 50.70° C., is made possible.

Evacuation unit 1190 comprises vacuum chamber 1106 which is notU-shaped, miniature vacuum pump 1109 suitable for producing a vacuumranging from 200-1000 millibar, conduit 1107 and control valve 1111through which subatmospheric fluid is discharged from chamber 1106, andminiature pressurized tank 1110 containing, e.g 100 ml, which deliversair through conduit 1112 and control valve 1108 to chamber 1106. If sodesired, a clear transmitting element need not be used, and vacuumchamber 1106 defined by lens 1104 will have an accordingly largervolume.

Control unit 1119 comprises the following essential elements:

a) Display 1115 of the energy density level of the monochromatic lightemitted by laser system 1116 and a selector for selecting apredetermined energy density.

b) Confirmation indicator 1120 which verifies that the selected energydensity is being applied to the skin. Control circuitry deactivates thelaser power supply if a beam having an energy density significantlylarger than the predetermined value is being fired.c) Display 1122 concerning the pulse structure, such as wavelength,pulse duration and number of pulses in a train.d) Control circuitry 1123 for selecting the time delay between operationof vacuum pump 1109 and laser system 1116.e) Selector 1124 for controlling the vacuum level in vacuum chamber 106by means of pump 1109.f) Control circuitry 1126 for controlling the vacuum duty cycle byregulating the operating cycle of vacuum pump 1109, the open and closetime of control valve 1111, the average vacuum pressure, the vacuummodulation frequency, and the repetition rate.g) Control circuitry 1143 for delivering fluid from positive pressuretank 1110 by controlling the duty cycle of control valve 1108.

Tank 1110, in which air having a pressure ranging from 1.2 atmospheresis contained, provides a fast delivery of less than 1 msec of air intochamber 1106, as well as a correspondingly fast regulation of the vacuumlevel therein by first opening control valves 1108 and 1111 andactivating vacuum pump 1109. After a sufficient volume of fluid, e.g 1ml, is delivered to chamber 1106, control valve 1108 is closed. Controlcircuitry 1126 and 1143 then regulate the operation of the controlvalves so to maintain a predetermined level of vacuum. Upon achievingthe predetermined vacuum level, control circuitry 1123 fires lasersystem 1116 after the predetermined time delay, which may range from1-1000 msec.

FIG. 25 illustrates apparatus 1270, which comprises a non-coherentintense pulsed light system similar to that described with respect toFIG. 19 and provided with Xe flashlamp 1201, such as one manufactured byLumenis, Deka, Palomar, or Syneron. Reflector 1202 reflects the emittedlight 1207 to light guide 1208. Distal end 1203 of light guide 1208 isseparated 1-2 mm from skin surface 1242 to allow for the generation of avacuum in vacuum chamber 1206 without compromising treatment efficacy bylimiting the protrusion of the skin target from the adjoining skinsurface 1242.

FIG. 26 illustrates the placement of apparatus 1370 onto arm 1310.Apparatus 1370 comprises handpiece 1301, evacuation unit 1390, and skinchiller 1300 for cooling the epidermis of arm 1310, which is heated as aresult of the impingement of monochromastic light thereon. Skin chiller1300 is preferably a metallic plate made of aluminum, which is incontact with the epidermis and cooled by a thermoelectric cooler. Thetemperature of the plate is maintained at a controlled temperature, e.g.0° C. The chilled plate is placed on a skin region adjacent to skintarget 1340. The epidermis may be chilled prior to the light treatmentby other suitable means, such as by the application of a gel or a lowtemperature liquid or gas sprayed onto the skin target.

It will be appreciated that the utilization of a U-shaped vacuum chamber1306 for the evacuation of vapors which condense on clear transmittingelement 1376 is particularly advantageous when a skin chiller inpermanent contact with the handpiece outer wall is employed. Such a skinchiller is illustrated in FIG. 26 or FIG. 15 f, resulting incondensation of vapors on the transmitting element that would not beevacuated without employment of an evacuation unit in accordance withthe present invention. When the skin chiller of FIG. 15 f is employed,the skin chiller is displaced, for example by a releasable attachmentmeans as shown in FIG. 2 e or by any other suitable method, such that itis contact with the vacuum chamber.

FIG. 27 schematically illustrates the effect of applying asubatmospheric pressure to a skin target, in accordance with the presentinvention, in order to enhance the absorption of light by blood vesselswithin the skin target. For clarity, the drawing illustrates the effectwith respect to a single blood vessel; however, it should be appreciatedthat many blood vessels contribute to the effect of increased bloodtransport whereby a plurality of blood vessels are drawn to theepidermis, resulting in increased absorption of the optical energy. Theprotrusion of the skin target relative to the adjoining skin surface isalso shown in disproportionate fashion for illustrative purposes.

The increase in light absorption within blood vessels due to theapplication of a vacuum in the vicinity of a skin target depends on thevacuum level, or the rate of vacuum modulation, and the skin elasticitywhich is reduced with increased age. As shown, blood vessel 1329 ofdiameter D is in an underlying position relative to vacuum chamber 1326.By applying a vacuum by means of evacuation unit 1390, blood flow isestablished in blood vessel 1329 in the direction of arrow M, due to adifference of pressures between points A and B closer and farther fromvacuum chamber 1326, respectively. If the blood vessel is a vein, theflow will be established in only one direction, due to the influence ofthe corresponding vein valve.

According to the Hagen-Poisseuille equation concerning the flow ofviscous fluids in tubes, the discharge from a tube and consequently theduration of flow therethrough depends on a pressure gradient along thetube, the fourth power of the diameter of the tube, and the lengththereof. For example, diameters of 100 microns are common forcapillaries adjacent to the papillary dermis at a depth of approximately200 microns and 500 micron blood vessel diameters can be found in thehair bulb at a depth of 3 mm. A typical blood vessel length isapproximately 1-2 cm. It will be appreciated that although the bloodvessel diameters generally increase with depth, the pressure gradientalong the blood vessel is smaller at deeper layers of the skin. As aresult, for a given pressure, such as the application of a zero millibarvacuum, each depth from the skin surface corresponds to a characteristictime response for being filled by blood. As a result, modulation of thevacuum by opening and closing control valve 1111 (FIG. 24) controls theflow of blood through blood vessels and consequently controls the degreeof light absorption by a blood vessel at a given depth from skin surface1342. In a realistic situation wherein a plurality of blood vessels arelocated within a skin target, each skin layer is characterized by adifferent modulation frequency which typically ranges between 100 Hz forupper layers and 1 Hz for the deep layers under the hair follicles. Byopening control valves 1108 and 1111 (FIG. 24) by a varying frequency,the operator may modulate the vacuum applied to the skin target andthereby vary the blood richness of different skin layers.

The operator typically determines an instantaneous modulation frequencyof control valves 1108 and 1111 by visually inspecting the skin targetand viewing the degree of redness thereat in response to a previouscontrol valve modulation frequency. In addition to improving thetreatment efficacy, an increased degree of redness within the skintarget advantageously requires a lower energy density of intense pulsedlight for achieving blood coagulation or blood heating resulting in theheating of the surrounding collagen. Alternatively, an errythema, i.e.skin redness, meter, e.g. produced by Courage-Hazaka, Germany, may beemployed for determining the degree of redness, in order to establishthe necessary energy density for the treatment.

For example, a modulation frequency as high as 40 Hz or the firing of aDye laser unit approximately 1/40 seconds after application of a, vacuummay be necessary for applications of port wine stains. In contrast, adelay of approximately a half second for fine wrinkle removal and ofapproximately 1 second for hair removal may be needed for a depth of 1-3mm under the skin surface.

FIG. 28 illustrates the concentration of a plurality of blood vessels1329 in a skin target 1340, which results in the increase of redness ofskin and enhanced absorption of light with respect to the hemoglobinabsorption spectrum and scattering properties of skin. Light absorptionis enhanced by a larger number of blood vessels per unit volume due tothe correspondingly larger number of light absorbing chromophores. Thebeneficial effect of vacuum assisted absorption by Dye lasers or anyyellow light, which is strongly absorbed by hemoglobin, is morepronounced on white or yellow skin not rich in blood vessels, such asthat of smokers. Such types of skin suffer from enhanced aging andrequire photorejuvenation, the efficacy of which is improved with theuse of the present invention. Enhanced absorption of light is alsoadvantageously achieved when infrared lasers and intense pulsed lightsources are employed.

FIG. 29 is a photograph illustrating the treatment of a fine wrinkle1401 by means of a vacuum assisted handpiece according to the currentinvention, which was taken one-half of a second after the application ofa vacuum. Circles 1402-4 indicate the sequential treatment spots. Thecolor in the circle 1403 has changed.

FIG. 30 illustrates apparatus 1570 which increases blood vesselconcentration within a skin target without use of a handpiece. Apparatus1570 comprises evacuation unit 1590 having a transparent vacuum chamber1501 made of a thin, transparent polymer 1506, such as polycarbonate orglass, which is transparent to visible or near infrared light. Vacuumchamber 1501 has a diameter of 5.20 mm and a height of approximately 1.3mm, in order to avoid excessive protrusion of the skin. Chamber 1501 ispreferably cylindrical, although other configurations are also suitable.Soft silicon rim 502 is adhesively affixed to the periphery of thechamber 1501, in order to provide good contact with skin surface 1542.Conduit 1503 in communication with control valve 1504 allows for theevacuation of vacuum chamber 1501 by means of a miniature vacuum pump(not shown) and control unit 1505. After chamber 1501 is placed on skintarget 1540, pulsed beam 1508 from any existing intense pulsed laser orlight source 1509 which operate in the visible or near infrared regionsof the spectrum may propagate therethrough and effect treatment of askin disorder. The advantage of this apparatus is its low price and itsability to interact with any intense pulsed laser or non-coherent lightsource which is already installed in a health clinic.

The absorption of visible intense pulsed light in blood vessels whenvacuum is applied to a skin target may be enhanced by the directingelectromagnetic waves to the skin target. Radio frequency wavesoperating in the range of 0.2-10 Mhz are commonly used to coagulate tinyblood vessels. The alternating electrical field generated by a bipolarRF generator, such as produced by Elman, USA, follows the path of leastelectrical resistance, which corresponds to the direction of blood flowwithin blood vessels.

FIG. 31 illustrates apparatus 1870 which comprises intense pulsed laseror intense pulsed light source 1821, RF source 1811, and evacuation unit1890. Evacuation unit 1890 comprises vacuum chamber 1801, which isplaced on skin surface 1802 to be treated for vascular lesions,miniature vacuum pump 1805, and control valve 1804 for regulating thelevel of the vacuum in chamber 1801. Clear transmitting element 1806 ispositioned in such a way that beam 1820 generated by light source 1821propagates therethrough and impinges skin surface 1802 at an angle whichis substantially normal to the skin surface.

RF source 1811 is a bipolar RF generator which generates alternatingvoltage 1807 applied to skin surface 1802 via wires 1808 and electrodes1809. Electric field 1810 generally follows the shape of blood vessels1813, which are the best electrical conductors in the skin. Due to theconcentration of blood vessels 1813 in the epidermis, the depth of whichbelow skin surface 1802 depending on the vacuum level and the frequencyof vacuum modulation, the combined effect of optical energy in terms ofbeam 1820 and pulsed RF field 1810 heats or coagulates the bloodvessels.

Control valve 1804 is regulated by means of control unit 1812. A firstcommand pulse 1 of control unit 1812 controls valve 1804 and a secondcommand pulse 2 controls a delayed radio frequency pulse as well as adelayed light source pulse.

Example 1

An experiment was performed to demonstrate the operating principles ofthe present invention in which transparent light diffusing adhesive“Magic Tape,” manufactured by 3M, having a thickness of 100 microns wasattached to the distal end of an Alexandrite laser unit having adiameter of 8 mm. The energy level of the laser beam is 11 J/pulse. Thelaser beam was directed to the white (rear) side of a black developedphotographic paper having a thickness of 300 microns. For comparison,the laser beam was also directed to the photographic paper without theuse of the adhesive tape.

The ablation of the black paper after the beam had propagated andscattered through the white paper provides a visual simulation of thecapability of the laser beam to penetrate transparent light-scatteringskin in order to treat black hair follicles (or any other type oflesion) under the skin.

The energy of the laser beam transmitted through the adhesive tape,which caused the laser beam to scatter, was measured by directing thebeam to an energy meter located at a distance of 1 mm from the distalend of the laser unit. The energy of the scattered laser beam droppedfrom 11 to 10 J. The results of this experiment indicate that thediffusively transmitting element did not absorb a significant amount ofenergy, since a loss of 10% is expected in any case due to Fresnelreflection.

When the laser beam was directed to the white (rear) side of a developedphotographic plate at a distance of 1 mm, an ablation of the black coloron the opposite side of the photographic paper resulted. There was nodifference in the results between usage of light diffusing tape or not.This experiment demonstrates that the performance of a non-coherentAlexandrite laser beam, according to the present invention, at adistance of 1 mm is essentially equal to the corresponding coherentlaser beam.

When the laser beam was directed, without the addition of lightdiffusing tape, at the photographic paper from a distance of at least 8mm, an ablation resulted that is identical to that which was generatedfrom a short distance of 1 mm. However, when light diffusing tape wasapplied to the exit aperture of the laser unit from a distance of atleast 8 mm, the scattered beam did not result in an ablation.Accordingly, the present invention allows for a high level of safety andlack of damage to bodily tissue when disposed at a relatively largedistance therefrom.

Example 2

In a second experiment a long pulse Alexandrite laser unit having awavelength of 755 nm, pulse duration of 90 msec, and having an energydensity of 25 J/cm² was used for hair removal. A diffusing unit with anultra-densely woven polymer-based diffuser having a half angle of 15degree produced by Barkan or a holographic diffuser produced by PhysicalOptics Corporation (USA) having a half angle of 40 degrees was employed.The diffusers were used in a one-time basis. Chilling gel was appliedbetween the diffuser and the skin.

Each pulse of a laser beam scattered by a diffusing unit formed a spotof 5.5 mm on-various skin locations including arms, bikini lines andarmpits of 10 patients. Full hair removal was noticeable immediatelyafter the firing of the laser beam. Each spot was compared to a controlarea with an identical diameter formed by an unscattered laser beamgenerated by the same laser unit with similar parameters, and similarresults were achieved. Hair did not return to those spots for a periodof one month.

Example 3

A long pulse Alexandrite laser unit having a wavelength of 755 nm, pulseduration of 40 msec, and having an energy level of 1.20 J is suitablefor hair removal.

The diameter of the diffusing unit is 7 mm, and its scattering halfangle is 60 degrees. A diffusing unit comprising a diffuser with a smallscattering angle, a highly divergent lens and a light guide is added tothe distal end of the laser unit.

The prior art energy density of 10.50 J/cm² is not significantly reducedwith the employment of a diffusing unit. The laser unit operates at 25J/cm² and generates a radiance of 8 J/cm²/sr. Since the acceptableradiance limit according to ANSI Z 136.1 is 4.3 J/cm^(2/)sr, bystandersare required to use protective eyeglasses with 50% optical attenuation,an attenuation similar to that of sunglasses and an order of 100,000less than typical protective eyeglasses worn during operation of a laserunit. For a larger target area, a scanner such as the Epitouch modelmanufactured by Lumenis may be used.

A diffusing unit having a diameter of up to 7 mm is particularlysuitable for lower energy lasers, which are relatively small, removehair at a slower speed from limited area and are inexpensive. Anapplication of such a laser, when employed with a diffusing unit,includes the removal of eyebrows.

Example 4

A pulsed Nd:YAG laser unit such as one produced by Altus (USA) or Deka(Italy) having a wavelength of 1064 nm, pulse duration of 100 msec, andhaving an energy level of 0.5-60 J is suitable for hair removal at anenergy density ranging from 35-60 J/cm².

A diverging unit with an array of focusing lenslets, an array of lensesprovided with reflective coating on its distal side, and a plurality ofconvex reflectors attached to a transparent plate is used, such that thediverging half angle is close to 60 degrees. When a laser beam having anenergy density of 40 J/cm² is generated, a radiance of 12.7 J/cm^(2/)srat the exit of the diverging unit is induced, approximately half of themaximal permitted radiance according to ANSI Z 136.1.

Example 5

A long pulse diode laser unit having a wavelength ranging from 810-830nm, or of 9.10 nm or 940 nm pulse duration ranging from 1.200 msec, andhaving an energy level of 0.5-30 J is suitable for hair removal at anenergy density ranging from 20-50 J/cm².

The diameter of the treated area, or spot size, ranges from 1.20 mm. Thediffusively transmitting element is preferably made from fused silica,sapphire, or is a holographic diffuser used in conjunction with a lightguide or with any other diffusing unit described hereinabove. Thescattering half angle is close to 60 degrees. A scanner may beintegrated with the diffusing unit. The delivery system to which thediffusing unit is attached may be a conical light guide, such as thatmanufactured by Coherent or Lumenis, a guide tube produced e.g. byDiomed or a scanner produced e.g. by Assa. With a diffusing unit havinga diameter of 5 mm and a laser beam generated with an energy density of20 J/cm² and a pulse duration of 100 msec, the radiance at the exit ofthe diffusing unit is 9.6 J/cm^(2/)sr, lower than the maximal permittedradiance value of 11.0 J/cm^(2/)sr.

Example 6

A miniature diode laser unit for home use operating at a wavelength ofapproximately 810 nm, or 940 nm, such as one produced by Dornier,Germany, and having a power level of 4 W is suitable for hair removal.The invention converts a continuous working diode laser unit, which isin a high safety class and usually limits operation to the medicalstaff, into a lower safety class, similar to non-coherent lamps of thesame power level.

The diffusing unit utilizes an angular beam expander with a convexreflector, a concave reflector having an inner diameter of 16 mm, a10-degree glass diffuser, and a light guide having a length of 20 mm andan inner diameter of 2 mm. The diameter of the treated area, or spotsize, is approximately 2 mm. The energy density at the exit of the lightguide is 30 J/cm² and the radiance thereat is approximately 10 J/cm²/sr.A scanner may be integrated with the diffusing unit. The diode laser mayalso be used without a scanner, in which case the laser will be pulsedfor a duration of approximately 300 msec.

Example 7

A Ruby laser unit having a wavelength of 694 nm, pulse duration rangingfrom 0.5-30 msec, and having an energy level of 0.2-20 J is suitable forhair removal.

The diameter of the treated area, or spot size, ranges from 1-20 mm. Thelarger spot sizes can be generated by Ruby lasers manufactured byPalomar, ESC and Carl Basel, which provide an energy density rangingfrom 10-50 J/cm². The smaller spot sizes can be generated by inexpensivelow energy lasers, which are suitable for non-medical personnel. Amulti-component diffusing or diverging unit may be used. The laser unitis much safer than a conventional laser unit

A scanner, such as manufactured by Assa of Denmark or by ESC, may beused to displace a reflected collimated beam from one aperture toanother formed within the diffusing or diverging unit. The scanning rateis variable, and the dwelling time at each location ranges from 20-300msec.

Example 8

High risk laser units, such as Nd:YAG having a wavelength of 1.32microns and manufactured by Cooltouch with a pulse duration of up to 40msec, a dye laser having a wavelength of 585 nm and manufactured byN-Light/SLS/ICN, or a Nd:Glass laser having a wavelength of 1.55 micronswith a pulse duration of 30 millisec may be used for non-ablative skinrejuvenation. This application is aimed at the treatment of rosacea,mild pigmented lesions, reduction of pore sizes in facial skin and mildimprovement of fine wrinkles, without affecting the epidermis. Theadvantage of these lasers for non-ablative skin rejuvenation is relatedto the short learning curve and more predicted results due to the smallnumber of treatment parameters associated with the single wavelength. Byimplementing a diffusing unit, the laser unit becomes safe and may beoperated by non-medical personnel.

An N-Light laser unit is initially operated at an energy density of 2.5J/cm² for collagen contraction. The addition of a diffusing unit makesthe laser unit as safe as an IPL. The addition of a multi-componentdiffusing or diverging unit with a divergent half angle of 60 degreesand an exit diameter of 5 mm results in a radiance level of 0.79J/cm^(2/)sr, which is equal to maximal accepted limit.

A laser beam may be generated with a considerably less expensive laserunit, having an energy level ranging from 0.5-3 J and a slow repetitionrate such as 1 pps, and generating a spot size ranging from 2-4 mm. Inthe case of wrinkle removal, the operator may follow the shape of thewrinkles with a small beam size. Such a non-coherent laser beam having abeam size of 2-4 mm is particularly suitable for aestheticians. Using adiffusing unit depicted in FIG. 10 b with a 10 degree diffuser and alight guide having a length of 30 mm results in a laser unit with aradiance of approximately 0.5 J/cm²/sr.

Example 9

A pulsed Nd:YAG laser unit having a wavelength of 1064 nm andmanufactured by ESC and having an energy level of 0.5-60 J is suitablefor treatment of vascular lesions. The pulse duration ranges from 1.200msec, depending on the size of the vessels to be coagulated (300 micronsto 2 mm) and the depth thereof below the surface of the skin. A LICAF(Litium Calcium Fluoride) laser unit at a wavelength of 940 nm may alsobe advantageously used for this application, and its associated laserbeam is better absorbed by blood than the Nd:YAG or Dye laser. A Dyelaser at a wavelength of 585 nm and manufactured by Candela may be usedto treat vessels located at a low depth below the skin surface, such asthose observed in port wine stain, telangectasia and spider veins.

The diameter of the treated area, or spot size, ranges from 1-10 mm,depending on the energy level. A multi-component diffusing or divergingunit is used, due to the relatively high energy density of greater than90 J/cm² needed for the treatment of deep vascular lesions. A scannermay be integrated with the diffusing unit.

Example 10

Q-Switch laser units having a pulse duration ranging from 10-100 nsecand having an energy density of 0.2-10 J/cm² is suitable for removal ofpigmented spots, mostly on the face and hands, as well as removal of atattoos. A Q-switched Ruby laser as manufactured by ESC or Spectrum, aQ-Switch Alexandrite laser manufactured by Combio, and a Q-Switch Nd:YAGlaser may be used for such an application.

The diameter of the treated area, or spot size, ranges from 1-10 mm,depending on the energy level. A diffusing unit utilizing twodiffusively transmitting elements is used, wherein one is fixed whilethe other is axially displaceable such that both elements areessentially in contact with each other in an active position, e.g. a gapof approximately 0.2 mm when a laser beam is fired. The gap between thetwo elements is approximately 15 cm when the laser is not fired. Thediameter of the diffusing unit is 6 mm. Each diffusively transmittingelement is preferably made from glass, sapphire or polymer.

The addition of such a diffusing unit with an axially displaceablediffuser to the aforementioned laser units is instrumental in renderingpigmented lesion and tattoo removal to be a considerably less riskyprocedure. Tattoo removal is achieved only by means of a laser beam, andis not attainable with intense pulse light sources.

The removal of pigmented lesions may also be performed with the use ofan Erbium laser unit operated at a wavelength of 3 microns. Mostpigmentation originates from the epidermis, and such a laser beampenetrates only a few microns into the skin. With implementation of adiffusing unit, this procedure may not necessarily be performed bymedical specialists. Aestheticians will be able to treat a large numberof patients, particularly since an Erbium laser is relativelyinexpensive.

Another application of the present invention involves the field ofdentistry, and relates to the treatment of pigmented lesions found onthe gums. Q-switched as well as Erbium lasers may be used for thisapplication.

Example 11

A CO₂ laser may be used for wrinkle removal. In prior art devices, sucha laser is used in two ways in order to remove wrinkles: by ablation ofa thin layer of tissue at an energy density greater than 5 J/cm² with aCoherent Ultrapulse, ESC Silktouch, or Nidek Coe laser and scanner for aduration less than 1 msec; or by non-ablative heating of collagen in theskin for lower energy densities, such as at 3 W, which may be achievedby operation of a continuously working ESC derma-K laser for 50 msec ona spot having a diameter of 3 mm.

With implementation of the present invention in which a multi-componentdiffusing or diverging unit is attached to a CO₂ laser, a laser beamhaving a wavelength of 10.6 microns may be generated. As opposed toother far infrared sources whose thermal and spectrally broad bandwidthinvolves less control of penetration depth, the interaction of a laserbeam with tissue according to the present invention is highlycontrollable and its duration can be very short.

The diffusing and diverging units are preferably made from a lensletthat is transparent to a CO₂ laser beam such as ZnSe or NaCL. Thediameter of the diffusing unit ranges from 1.10 mm. The divergent angleis greater than the minimal acceptable value so as to produce a radiancelevel at the exit beam that is essentially eye safe.

During ablation, a clear transmitting element of the diffusing unit isseparated from the tissue to be treated by a thin spacer having athickness of approximately 1 mm to allow for the evacuation of vapors orsmoke produced during the vaporization process.

Similarly an Erbium laser unit operating at an energy density above 2J/cm² and generating a laser beam greater than 3 microns may be used forwrinkle removal. Ablation is shallower than attained with a CO₂ laserand application of an Erbium laser unit can be extended to tattoo orpermanent make up removal.

Example 12

A Nd:YAG or other laser unit may be used for treatment of herpes. Adiode laser with selective absorption of Cyanin green or other materialsby fatty lesions may be used for treatment of acne. Both of these lasersmay be used for treatment of hemorroids and for podiatric lesions on thefeet.

Example 13

A dye laser unit operating at a wavelength of approximately 630 nm or585 nm, or at other wavelengths which are absorbed by natural porpherinspresent in P acne bacterias, such as produced by Cynachore or SLS, aswell as a laser unit operating at 1.45 microns as produced by Candella,may treat acne lesions. The addition of a diffusing or diverging unit tothe laser unit may considerably enhance eye safety and simplify the useof the laser unit for such treatments by nurses and non-medical staff.

Example 14

CO₂, diode and Nd:YAG laser units operating at an average power ofapproximately 1-10 W are currently used by physicians to treat pain. Theaddition of a diffusing unit may enable the use of a highly safe devicefor that procedure in pain clinics by non-medical personnel. Each laserunit may generate a number of repetitively occurring sets of pulses,during a period of approximately 3 seconds. The delivery system of thelaser beam may be an articulated arm or an optical fiber.

Example 15

A diode laser unit manufactured by Candella (USA) generating a laserbeam with an energy density of 10 J/cm², a wavelength of 1445 nm, apulse duration of 100 msec and a spot size of 3 mm is suitable fornon-ablative photorejuvenation.

A diverging unit with a single converging lens focuses the beam to afocal zone 1.5 mm proximate to the distal end of the diverging unit andproduces a half angle divergence of 45 degrees. The diverging unit isprovided with a shield located 10 mm distal to the focal point, whereatthe energy density is reduced to an eye safe level of 0.2 J/cm² and aspot size is 23 mm.

Example 16

It is advantageous to use an eye-safe laser unit for welding. Theemployment of a diffusing unit is an excellent way to reduce the risksassociated with laser welding.

When welding thin transparent parts, such as those made from plastic,e.g with a diode laser unit, it is often advantageous to employ a largesurface scanner or a large diameter beam which will irradiate a largesurface area and selectively activate all targets with appropriatechromophores (by heat). Such a scanner is in contrast to a scanner whichis specifically targeted to the geometrical locations at which weldingmaterials are present. The dwelling time of the welding laser beam atthe targets depends on the size of the welding element and the depth ofmaterial to be melted. The dwelling time is also dependent on the sizeof a target treated in photothermolysis. As an example, welding a striphaving a thickness of 50 micron to a substrate necessitates a dwellingtime of approximately 1 msec, while a strip having a thickness of 200microns requires a dwelling time of 16 msec. The dwelling time isproportional to the square of the thickness. Some welding chromophoresare transparent in the visible part of the spectrum, but exhibit strongabsorption in the near infrared part of the spectrum.

Example 17

Another industrial application for the present invention is associatedwith microstructures to be evaporated. Paint stains or ink may beselectively evaporated from surfaces such as clothes, paper and othermaterials that need cleaning by use of various pulsed lasers. Oneexample of this application is related to the restoration of valuedantiques. Another example is the selective vaporization of metallicconductors which are coated on materials such as glass, ceramics orplastics. Vaporization of metallic conductors can be achieved with apulsed laser, which is generally separated by a short distance from atarget and whose beam has a duration ranging from 10 nanoseconds to 10milliseconds. Pulsed Nd:YAG lasers are the most commonly used ablativeindustrial lasers, although other lasers are in use as well. PulsedNd:YAG industrial lasers may attain an energy level of 20 J concentratedon a spot of 1 mm, equivalent to an energy density of 2000 J/cm². Theaddition of a diffusing unit to an industrial laser considerablyincreases the safety of the ablative device.

Pulsed Nd:YAG laser units are also suitable for improving the externalappearance of larger structures, such as the cleaning of buildings,stones, antique sculptures and pottery. The laser units in use today areextremely powerful, having a continuously working power level of up to 1kW, and are therefore extremely risky. The addition of a diffusing unitconsiderably improves the safety of these laser units.

A diffusing unit, when attached to an Excimer laser unit, is suitablefor photo-lithography, or for other applications which use an Excimerlaser unit for a short target distance.

With the addition of a multi-component diffusing or diverging unit, allof these applications become much safer to a user.

Example 18

An experiment was performed to determine the time response of skinerythema following application of a vacuum onto various skin locations.A pipe of 6 mm diameter was sequentially placed on a hand, eyeperiphery, arm, and forehead at a subatmospheric pressure ofapproximately 100 millibar. The skin locations were selected based onthe suitability for treatment: the hands and eye periphery for wrinkleremoval, arm for hair removal, and forehead for port wine staintreatment. The vacuum was applied for the different periods of time of1/10, ¼, 1, 2, 3 seconds and then stopped. The erythema level anderythema delay time were then measured.

The response time of the hand and eye periphery was ½ sec, the responsetime of the arm was 1 second and the response time of the forehead was ½second. Accordingly, the experimental results indicate that thenecessary delay between the application of the vacuum and firing of thelaser or intensed pulsed light is preferably less than 1 second, so asnot to delay the total treatment time, since the repetition rate of mostlaser or intensed pulsed light sources is generally less than 1pulse/sec.

The erythema delay time was less than 1 second, and therefore theexperimental results indicate that patients will not sense appreciableaesthetic discomfort following treatment in accordance with the presentinvention.

Example 19

An intense pulsed light system comprising a broad band Xe flashlamp anda cutoff filter for limiting light transmission between 755 nm and 1200nm is suitable for aesthetic treatments, such that light deliveredthrough a rectangular light guide is emitted at an energy density of 20J/cm² and a pulse duration of 40 milliseconds, for hair removal withrespect to a treated area of 15×45 mm.

While efficacy of such a light system for the smoothening of finewrinkles, i.e. photorejuvenation, is very limited by prior art devices,due to the poor absorption of light by blood vessels at thosewavelengths, enhanced light absorption in targeted skin structures inaccordance with the present invention would increase the efficacy.

A transparent vacuum chamber of 1 mm height is preferably integrallyformed with a handpiece through which intense pulsed light is directed.A diaphragm miniature pump, such as one produced by Richly Tomas whichapplies a vacuum level of 100 millibar, is in communication with thechamber and a control valve is electronically opened or closed. When thecontrol valve is opened, the pressure in the vacuum chamber is reducedto 100 millibar within less than 10 milliseconds. As a result of theapplication of vacuum, the skin slightly protrudes into the vacuumchamber at an angle as small as 1/15- 1/45 radian (height divided bysize of skin target) and a height of 1 mm. Blood is drawn into the drawnskin target, which achieves a much pinker hue and therefore has a higherlight absorbence. The increased redness of the skin increases the lightabsorption by a factor of 3. As a result, the efficacy of theaforementioned light system is similar to that of a prior art systemoperating at 60 Joules/cm², which is known to provide adequate resultsin wrinkle removal procedures. At energy density levels as high as 20J/cm², it is preferable to chill the epidermis in order to avoid a riskof a burn. Epidermis chilling is accomplished by means of an aluminumplate, which is chilled by a thermoelectric chiller. The plate is incontact with the skin and chills the skin just before the handpiece ismoved to the chilled skin target, prior to treatment.

The invention has thereby converted an intense pulsed light device forhair removal into an efficient photorejuvenation device as well.

Example 20

An Nd:YAG laser operating at 1064 nm, 90 milliseconds pulse duration,and energy density of 70 J/cm² is suitable for prior art hair removalhaving a spot size of 7 mm. By prior art hair removal, absorption oflight in the hair shaft melanin is limited, with a contributory factorin hair removal being attributed to the absorption of light by blood inthe hair follicle bulb zone. Since the energy density level of 70 J/cm²is risky to the epidermis of dark skin, it would be preferable tooperate the laser at 40 J/cm².

A vacuum chamber is preferably integrally formed with a handpiecethrough which intense pulsed light is directed, at a distance of 1 mmfrom the skin target. A vacuum is applied to the skin target for 2seconds. The blood concentration near the follicle bulb and in the bulgeat a depth of 4 and 2 mm, respectively, is increased by a factor of 2.As a result the laser is operated with the same efficacy at energylevels closer to 40 J/cm² and is much safer.

Example 21

A Dye laser emitting light at a wavelength of 585 nm, with a spot sizeof 5 mm and pulse duration of 1 microsecond, is used by prior artmethods for treatment of vascular lesions, such as telangectasia, andport wine stains, at an energy density level ranging from 10.15 J/cm²and for the smoothing of wrinkles at an energy density level of 3-4J/cm². Some disadvantages of the prior art method are the purpura thatis often produced on the skin during vascular treatments and the verylarge number of treatments (more than 10) which are necessary for thesmoothening of wrinkles.

By applying a controlled vacuum to a vacuum chamber in contact with askin target, having either a moderate vacuum level of approximately 600miilibar or a vacuum which is modulated at a frequency of 10 Hz for 1seconds prior to the firing of the laser, the efficacy of the laser isenhanced. Consequently it is possible to treat vascular lesions at 7J/cm² without creating a purpura and to remove wrinkles with a muchsmaller number of treatments (5).

Example 22

A prior art diode laser operated at 810 nm or a Dye laser is suitablefor treating vascular rich psoriatic skin, wherein the treated area perpulse is approximately 1 cm². By employing a vacuum chamber attached tothe distal end of the handpiece of either of these lasers, blood isdrawn to the lesion and treatment efficacy is improved. The vacuum maybe applied for 2 seconds prior to firing the laser beam.

Example 23

A deep penetrating laser, such as a pulsed diode laser at 940 nm, anNd:YAG laser, or an intense pulsed light source operating at an energydensity of 30 J/cm², is suitable for thermally damaging a gland, when avacuum chamber is attached to the distal end of the handpiece thereof.When vacuum is applied for a few seconds, e.g. 1.10 seconds, above agland such as a sweat gland, excessive blood is drawn into the gland.After the pulsed laser beam is directed to the skin, the absorption ofthe laser beam by the drawn blood generates heat in the gland, which isthereby damaged. It is therefore possible to more efficiently thermallydamage glands with a laser or intense pulsed light source when vacuum isapplied to the skin.

Example 24

By placing a vacuum chamber on a skin target in accordance with thepresent invention prior to the firing of an intense pulsed light source,the treatment energy density level for various types of treatment issignificantly reduced with respect with that associated with prior artdevices. The treatment energy density level is defined herein as theminimum energy density level which creates a desired change in the skinstructure, such as coagulation of a blood vessel, denaturation of acollagen bundle, destruction of cells in a gland, destruction of cellsin a hair follicle, or any other desired effects.

The following is the treatment energy density level for various types oftreatment performed with use of the present invention and with use ofprior art devices:

-   -   a) treatment of vascular lesions, port wine stains,        telangectasia, rosacea, and spider veins with light emitted from        a dye laser unit and having a wavelength of 585 nm: 5-12 J/cm²        (present invention), 10-15 J/cm² (prior art);    -   b) treatment of vascular lesions, port wine stains,        telangectasia, rosacea, and spider veins with light emitted from        a diode laser unit and having a wavelength of 940 nm: 10-30        J/cm² (present invention), 30-40 J/cm² (prior art);    -   c) treatment of vascular lesions with light emitted from an        intense pulsed non-coherent light unit and having a wavelength        of 570-900 nm: 5-20 J/cm² (present invention), 12-30 J/cm²        (prior art);    -   d) treatment of vascular lesions with light emitted from a KPP        laser unit manufactured by Laserscope, USA, and having a        wavelength of 532 nm: 4-8 J/cm² (present invention), 8.16 J/cm²        (prior art);    -   e) photorejuvination with light emitted from a dye laser unit        and having a wavelength of 585 nm: 2-4 J/cm² and requiring 6        treatments (present invention), 2-4 J/cm² and requiring 12        treatments (prior art);    -   f) photorejuvination with light emitted from a an intense pulsed        non-coherent light unit and having a wavelength ranging from        570.900 nm: 5.20 J/cm² (present invention), approximately 30        J/cm² (prior art);    -   g) photorejuvination with a combined effect of light emitted        from an intense pulsed non-coherent light unit and having a        wavelength ranging from 570-900 nm and of a RF source: 10 J/cm²        for both the intense pulsed non-coherent light unit and RF        source (present invention), 20 J/cm² for both the intense pulsed        non-coherent light unit and RF source (prior art); and    -   h) hair removal with light emitted from a Nd:YAG laser unit and        having a wavelength of 1604 nm: 25-35 J/cm² (present invention),        50-70 J/cm² (prior art).

While some embodiments of the invention have been described by way ofillustration, it will be apparent that the invention can be carried intopractice with many modifications, variations and adaptations, and withthe use of numerous equivalents or alternative solutions that are withinthe scope of persons skilled in the art, without departing from thespirit of the invention or exceeding the scope of the claims.

1. An apparatus for enhancing the absorption of light in targeted skinstructures, comprising: an intense pulsed light source; a U-shapedevacuation chamber positionable on a skin target; a handpiece fordirecting intense pulsed light to the skin target which is connected to,or integral with, the evacuation chamber; a clear transmitting elementmounted in the distal end of the U-shaped evacuation chamber, thetransmitting element being transparent to intense pulsed light directedto the skin target and suitable for transmitting the intense pulsedlight in a direction substantially normal to a skin surface adjoiningthe skin target; a rim for sealing the peripheral contact area betweenthe skin surface adjoining the skin target and the wall of thehandpiece; and means for applying a vacuum to the evacuation chamberincluding a first conduit and a second conduit in communication with theU-shaped evacuation chamber, the second conduit including a distalopening that can be occluded during vacuum application, the level of theapplied vacuum suitable for drawing the skin target to the evacuationchamber and for increasing the concentration of blood and/or bloodvessels within a predetermined depth below the skin surface of the skintarget, optical energy associated with the directed intense pulsed lightbeing absorbed within the predetermined depth.
 2. The apparatusaccording to claim 1, wherein the vacuum applying means comprises avacuum pump and at least one control valve.
 3. The apparatus accordingto claim 1, further comprising control means for controlling operationof the vacuum pump, the at least one control valve, and the intensepulsed light source.
 4. The apparatus according to claim 3, wherein thecontrol means is suitable for firing the intense pulsed light sourceafter a predetermined delay following operation of the vacuum pump. 5.The apparatus according to claim 3, wherein the control means issuitable for firing the intense pulsed light source after apredetermined delay following opening of the at least one control valve.6. The apparatus according to claim 5, wherein the control means issuitable for increasing the pressure in the evacuation chamber toatmospheric pressure following deactivation of the intense pulsed lightsource, to allow the effortless repositioning of the evacuation chamberto a second skin target.
 7. The apparatus according to claim 3, furthercomprising a pulsed radio frequency (RF) source for directing suitableelectromagnetic waves to the skin target.
 8. The apparatus according toclaim 7, wherein the frequency of the electromagnetic waves ranges from0.2 to 10 MHz.
 9. The apparatus according to claim 7, wherein the RFsource is a bipolar RF generator which generates alternating voltageapplied to the skin surface via wires and electrodes.
 10. The apparatusaccording to claim 7, wherein the control means is suitable fortransmitting a first command pulse to the at least one control valve anda second command pulse to both the intense pulsed light source and RFsource.
 11. The apparatus according to claim 3, further comprising anerythema sensor, said sensor suitable for measuring the degree of skinredness induced by the vacuum applying means.
 12. The apparatusaccording to claim 11, wherein the control means is suitable forcontrolling, prior to firing the light source, the energy density of thelight emitted from the light source, in response to the output of theerythema sensor.
 13. The apparatus according to claim 1, wherein theintense pulsed light source is selected from a group comprising a Dyelaser, Nd:YAG laser, Diode laser, Alexandrite laser, Ruby laser, Nd:YAGfrequency doubled laser, Nd:Glass laser and a non-coherent intense pulselight source.
 14. The apparatus according to claim 1, wherein the lightemitted from the light source has any wavelength band between 400 nm and1800 nm.
 15. An apparatus for enhancing the absorption of light intargeted skin structures, comprising: an intense pulsed light source; ahandpiece for directing light from the intense pulsed light source tothe targeted skin structures, the intense pulsed light source connectedto, or integral with, the handpiece, the handpiece further comprising:an evacuation chamber defined by a wall of the handpiece, the evacuationchamber positionable on a region of skin including the targeted skinstructures; a transmitting element mounted in the distal end of theevacuation chamber, the transmitting element being substantiallytransparent to the light directed to the targeted skin structures, andsuitable for transmitting the light in a direction substantially normalto a skin surface of the region of skin including the targeted skinstructures; and a rim on an end of the wall for sealing a peripheralcontact area between the skin surface and the wall of the handpiece; avacuum system for applying vacuum to draw the region of skin includingthe targeted skin structures into the evacuation chamber; and a firstconduit and a second conduit defined in the evacuation chamber, thefirst conduit communicating vacuum to the evacuation chamber, the secondconduit including a distal opening that can be occluded during vacuumapplication, optical energy associated with the light being absorbedwithin a predetermined depth below the skin surface of the skin target.16. The apparatus of claim 15 wherein the vacuum system is configured toapply a level of vacuum suitable for increasing the concentration ofblood and/or blood vessels within the predetermined depth
 17. Theapparatus of claim 15 wherein the vacuum system comprises a vacuum pumpand at least one control valve associated with the first conduit. 18.The apparatus of claim 17 further comprising control means forcontrolling operation of the vacuum pump, the at least one controlvalve, and the intense pulsed light source.
 19. The apparatus of claim18 wherein the control means is suitable for firing the intense pulsedlight source after a predetermined delay following operation of thevacuum pump.
 20. The apparatus of claim 18 wherein the control means issuitable for firing the intense pulsed light source after apredetermined delay following opening of the at least one control valve.21. The apparatus of claim 18 wherein the control means is suitable forincreasing the pressure in the evacuation chamber to atmosphericpressure following deactivation of the intense pulsed light source, toallow the effortless repositioning of the evacuation chamber to a secondskin target region.
 22. The apparatus of claim 15 wherein the intensepulsed light source is selected from the group comprising a dye laser, aNd:YAG laser, a diode laser, an alexandrite laser, a ruby laser, aNd:YAG frequency doubled laser, a Nd:Glass laser and a non-coherentintense pulse light source.
 23. The apparatus of claim 15 wherein thelight emitted from the intense pulsed light source has one or morewavelengths from about 400 nm to about 1800 nm.
 24. The apparatus ofclaim 15 wherein the intense pulsed light source is a diode laser. 25.The apparatus of claim 15 wherein the intense pulsed light source is anon-coherent intense pulse light source.
 26. The apparatus of claim 15wherein the second conduit includes a valve for occluding the distalopening.
 27. The apparatus of claim 26 further comprising a controlleradapted to operate the vacuum system, the valve for occluding the distalopening, and the intense pulsed light source.